Five months after its unveiling in early February, Apple is finally ready to release its next-gen operating system for the Mac. On Monday, the company released the golden master of OS 10.8 Mountain Lion to developers so they can begin submitting their Mountain Lion apps before the platform launches on the Mac App Store later this month for $19.99.

Apple sent an email to its registered developers on Monday with instructions. Here's what it said:

Make sure your apps take advantage of the great new features in OS X Mountain Lion when the world's most advanced operating system ships to millions of customers worldwide. Download OS X Mountain Lion GM seed and Xcode 4.4 GM seed, now available on the Mac Dev Center. Build your apps with these latest seeds, then test and submit for review. You can also submit iOS apps that take advantage of the new cross-platform Game Center Groups, so they'll be available when OS X Mountain Lion ships.

Apple hasn't said when it plans to release the public edition of Mountain Lion, but given the release of the golden master, which in hardware and software terms is essentially the finished product, or the mold from which all other copies are mass-produced, the official release will be coming very soon. Apple has not released a specific time or date, but many analysts expect Mountain Lion to be launched to the public within the next two weeks.

Mountain Lion: A Bridge Between iOS And Mac

Apple's current Mac operating system, Mac OS X Lion, was released in July 2011, and was the first Mac operating system completely downloadable over the Mac App Store. Mac OS X Lion included some of the most intuitive features from the iPad, such as adding multi-touch gestures like swiping and tapping directly onto the Mac's trackpad, and added support for full-screen apps, a new application viewer called Launchpad, and the company's cloud computing system for effortless synching and managing information across devices called iCloud.

Mountain Lion, which was unveiled in early February, will include many features from Apple's popular iOS mobile operating system, including the ability to message iPhone or iPad owners with its free messaging platform, an enhanced Notification Center, and new ways to share to social networks likeFacebook and Twitter.

We see that people are in love with a lot of apps and functionality here, Apple CEO Tim Cook said in an interview with The Wall Street Journal. Anywhere where that makes sense, we are going to move that over to Mac. 

Major Features Of Mac OS X Mountain Lion

Most of Mountain Lion's features were announced in February, but at WWDC 2012 in June, Apple announced even more features for Mountain Lion, including many that will also be added to iOS 6. Here's a breakdown of all of the new features coming in Mountain Lion:

Messages: In iOS 5, Apple dumped SMS text messaging on the iPhone and iPad and replaced it with a free platform called iMessage, a BlackBerry Messenger-type service that allowed Apple consumers to freely message each other text, photos, and videos to and from any iPhone, iPad and iPod Touch.

Messages is essentially iMessage for the Mac. It lets one send free and unlimited text messages from a Mac to anyone on an iPhone, iPad, iPod Touch, or on another Mac, letting users continue their conversations on any Apple device. As with iMessage, users can also send rich text, photos, contacts, locations, and even 1080p HD video to their friends. Furthermore, Messages supports FaceTime -- along with other instant messaging systems like AIM, Yahoo!, and Google Talk -- so users can pick up their chats no matter where they started.

Notification Center: Before Apple added the Notification Center to the iPad and iPhone, new texts and app alerts interrupted whatever the user was doing by popping a message directly in the middle of the screen. The Notification Center solved this annoyance by making notifications into small bars that appeared at the top of the device's screen momentarily, and those incoming notifications also did not interrupt the user's activities.

Apple wants its users to stay up-to-date across all of their devices, which is why the company added the Notification Center to the Mac in OS X Mountain Lion. By swiping the Mac trackpad with two fingers from right to left, the Mac Notification Center appears on the right side of the screen. Notifications from apps like Messages, Game Center, Mail, Calendar, Reminders, and other downloadable third-partyapps from the Mac App Store will tell you when there's something you should see. Like the iOS Notification Center system, users can choose which apps they want alerts from, and users can easily hide the Notification Center with a simple swipe.

Twitter Integration: Apple understands that people love and rely on Twitter to engage in the greater social community, and in iOS 5, the company gave its iPhone, iPad and iPod Touch users the ability to tweet from almost any app. Users could tweet photos, links, locations and webpages effortlessly. In less than a year, this platform has become huge for both Apple and Twitter: iOS 5 users sent more than 10 billion tweets since the platform went live in October.

With OS X Mountain Lion, this deep Twitter integration has reached the Mac, giving desktop users the ability to tweet out directly from apps like Safari, Photo Booth or iPhoto. Just like iOS 5, a Tweet Sheet pops up, with a paper clip over any attached image or website, and the user can write their message, add a location if they want, and send it out from there. It's simple, clean, and fast.

Facebook Integration: After successfully baking Twitter directly into the OS software, Apple has decided to open up built-in support for Facebook. Now, after signing into their account just once, users will be able to share content -- text, links and photos -- onto their or others' Walls, sync their Contacts with their profile photos from Facebook, and receive notifications over the Notification Center.

Safari: Apple's browser has become a big hit on the iPhone and iPad: Safari accounts two-thirds of all mobile web traffic. In Mountain Lion, Apple is bringing many of the best features from the mobile experience to the Mac. But Apple has also learned from its rivals: Like Google Chrome, the new version of Safari will include just one search bar for web addresses and search terms. Other than that, the experience looks just like iOS: Tab View allows you to see your webpages in open tabs, which can be swiped to switch between them. A new feature called iCloud Tabs also makes the browsing experience from mobile to Mac much more fluid: iCloud Tabs remembers where you were on one device, and automatically synchs it to the others, whether you own an iPad or iPhone. But one of the best features of the new Safari on Mountain Lion is the ability to read pages from your Reading List without an Internet connection.

Notes: Finally, Apple created a proper notes application for the Mac. Until this point, Mac users made do with an app called Stickies, which allowed them to create virtual multi-colored sticky notes and place them all over the computer screen. This app, while fulfilling a need for notetakers, had no way to search the notes or organize them efficiently.

This has all changed in OS X Mountain Lion. The new Notes application on the Mac takes after the app with the same name on the iPhone and iPad, which lets users create and search notes in a clean and easy-to-use interface. On the Mac, however, users will also get a chance to add photos, movies and links to their notes, as well as rich text, bullet points and formatted lists. For those users that will miss Stickies, Apple also allows anyone to tear the note right out of the Notes app and stick it anywhere on their desktop for easy access.

Game Center: The iPhone, iPad, and iPod Touch were all great devices for playing cheap, good-looking virtual games, but before iOS 5 came along, there was no way to track and organize your progress, especially comparing it to other customers playing the same game on their Apple devices. With the introduction of Game Center on iOS 5, Apple allowed users to create accounts, keep track of their awards and achievements in games, and even compete with friends, or find friends to compete with.

But then, Apple thought: Why should iOS have all the fun? With Game Center coming to the Mac, desktop users can play head-to-head and turn-based games against friends and competitors on any Mac or iOS device like iPhone, iPad or iPod Touch. Game Center also suggests games you might like, helps you find Game Center players from around the world to play against, and provides a leaderboard of the best players in each game.

Reminders: In iOS 5, Apple added a new app called Reminders, which lets users create organized, virtual reminders on their iPhone or iPad. Users can program their Apple devices to remind them to do something at a certain time or upon arriving at a certain place, which is accomplished via text notification. In OS X Mountain Lion, users can better set and organize reminders on their Macs, which are then synched across every device via iCloud.

Airplay Mirroring: One of the best -- yet most underrated -- features on iOS 5 was the ability to mirror whatever was on your iPad or iPhone 4S directly on a television hooked up to an Apple TV. In other words, iPad and iPhone 4S users could display movies, presentations, slideshows, photos, and websites onto a larger television screen wirelessly and seamlessly.

Finally, this incredible feature is coming to the Mac in OS X Mountain Lion. Users can stream videos, presentations, spreadsheets, or anything on their desktop screen directly onto their television sets.

Share Sheets: It's extremely easy to share photos or links on the iPhone or iPad. A box with an arrow appears on almost every page, which allows users to book mark pages, add them to the Reading List for later reading, mail the page to a friend, tweet it out to Twitter followers, or print out the page on a nearby printer.

In OS X Mountain Lion, Apple added the Share button to most apps within Mountain Lion, which similarly lets users add pages or links to their reading list, bookmark them on their browser, e-mail or tweet them out, or send them via Messages or iMessage. Not every sharing option applies to every page you see on the Mac, but Apple tailors sharing options based on the app you're using. For instance, some sites may allow you to share the page on Vimeo or Flickr, while others only allow Twitter.

Power Nap: Like the iPhone and iPad, Apple has changed the software inside the Macs so they can update even while they sleep. The feature is called Power Nap, which automatically updates your Mail, Contacts, Calendar, Notes, Reminders, Documents and other information in iCloud, such as Photo Stream and Find My Mac. As long as the Mac is connected to a power source, it can automatically download software updates (with the right preferences) and even back up information using Time Machine.

Gatekeeper: An intimidating new security feature for the Mac? Yes, please! Apple wants you to be safe and secure, and know that whatever app you're downloading from the Mac App Store can be trusted. To achieve this level of safety, Apple has created the Developer Program, which gives each developer a unique ID and digital signature on their apps. The Mac sees and understands this digital signature and knows that the application doesn't contain malware or hasn't been tampered with. If your preferences don't match your current needs, users can also temporarily override their own settings by Control-clicking the app and installing it.

Beyond the Mac App Store, Gatekeeper allows Mac users to control what apps they install and use. Apple added more optional security features, like requiring a password for sleep and a screen saver or disabling automatic login, but it's all in the name of giving the user more control over their privacy and security.

Features For China: Apple didn't forget about its huge base in Asia. In OS X Mountain Lion, Apple has added support for many Chinese services and features, including the entire Chinese dictionary and an improved text input to make typing in Chinese faster, easier, and significantly more accurate, letting users type in any one of eight new fonts. In addition, Apple made Mountain Lion accessible with mail services like 163, 126 and QQ, as well as China's leading search engine in Baidu, which is now a built-in option for Safari. Similar to the integration with Twitter and Facebook, Chinese users can also post directly from the Web to different apps, including video apps like Youku and Tudou, as well as the Chinese equivalent to Twitter called Sina Weibo.

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Which of these features in Mountain Lion are you most excited for? Let us know in the comments section below.