iCloud, Apple's ambitious cloud-based music, video, photo and data automatic backup and push out service, has finally been released but it's in beta form and out only to developers.

The iCloud.com web interface for developers has everything you want and more. It features all the new web apps for Mail, Calendar, Contacts, etc. In addition, it will allow users to view their iWork documents (Pages, Keynote, and Numbers) that are stored in the cloud and will also feature Find my iPhone as an integrated web app.

The basic iCloud service will be free but you'll get only up to 5GB storage space. If you want 10GB extra, you'll need to pay $20 per year. Want more? 20Gb will cost you $40 per year while 50GB will set you back by $100 per year. Expect a bumper deal for larger size in the near future.

The extra storage space can be purchased via iOS 5′s settings application by end users.

Sounds pricey compared to Amazon Cloud Drive as the latter too offers 5GB of free storage and for additional 20GB, you only need to pay $20 and for 50GB you need to pay $50. In other words, anything above 5GB, you get to pay $1 per GB annually and you can upgrade storage space up to 1000GB.

However, heavy iWork users will be happy to know that Apple will not count Photo Stream images that stays in the cloud for 30 days against their overall storage usage. In Amazon's case, photos count towards total tally.

Moreover, Apple promises that even 5GB of free storage will be enough for most users. "Your purchased music, apps, and books, as well as your Photo Stream, don’t count against your free storage. Since your mail, documents, Camera Roll, account information, settings, and other app data don’t use as much space, you’ll find that 5GB goes a long way," Apple said on the iCloud Web site.

Incidentally, last month, Amazon beefed up its Cloud Drive and Cloud Player storage plans by offering unlimited storage space for music (though for a limited time) and free storage space for all Amazon MP3 purchases.

The online retail giant also extended its Cloud Player (music player) for web support to Apple's iPad. Cloud Player also lets customers play music stored in the cloud on any device including Android phone, Android tablet, Mac and PC.

Meanwhile, MobileMe users will also be happy to know that Apple is automatically migrating their accounts to iCloud. In other words, your old MobileMe username and password will now function as your new iCloud Apple ID.

However, for the time being, iCloud does not support MobileMe's web apps, except for Find my iPhone though Mail, contacts, calendar, and the rest of the suite work perfectly with native apps.

The launch of iCloud (even Beta version) is a significant step for Apple because the service was one of main focus of Apple Worldwide Developers Conference (WWDC) 2011 held in June.

In fact, iCloud is so important to Apple that none other than Steve Jobs himself presented it to thousands of developers who had assembled in Moscone Center in San Francisco.

iCloud represents a major new direction for Apple, which sees it as a way of tying together its various desktop and mobile platforms (Mac OS X Lion and iOS 5 users), as well as providing an additional method for delivering media to users.

Moreover, unlike existing consumer-focused cloud-based services offered by others, including Google’s Music Beta digital locker and Amazon Cloud Drive, that requires users to manually upload their songs or data, iCloud automatically scans a user's library and make mirror copies available instantly on any Apple device.

And, if you're wondering what can be stored in iCloud, the answer is - practically everything that is digital. In iCloud, one can store contacts, calendars, mail and documents. One can also store music, photos, videos, apps, and e-books (iBooks). Additionally, the iCloud can be a storage for APIs.

The best feature of iCloud is probably iMatch, Jobs said. For just a flat $24.99 annual fee, iMatch will match the ripped songs of the user with 18 million+ songs in iTunes and upgrade them to higher quality 256kbps AAC DRM-free.

The remaining songs that could not be matched has to be uploaded manually. "First time we've seen this in the music industry," Jobs said. "If you don't think we're serious about this, you're wrong."

According to Jobs, iCloud means the end of file storage system. iCloud "is going to be pretty big" as everything is now automatic, seamless and effortless, he said at the WWDC.

Compared to Amazon Cloud Drive, iCloud is better at least for Apple fans because with Cloud Drive, you can access the files from any device as long as they support Flash. It means Cloud Drive is useless for any Apple product since they do not support Flash.

iCloud is also more convenient than Google Music Beta Digital Locker as it is only a part of Google's "cloud" suite and there's no one-stop destination that hosts all your media needs.

However, there’s a downside to iCloud. iCloud can only offer limited storage days – 30 days. It doesn't act as your warehouse. It can't also save all your data. But it does make sure that everything is synced and backed up properly as promised.

iCloud will not be officially released to the public until later this Fall with the arrival of iOS 5.