The release of iCloud Beta marks technology giant Apple's maiden venture into cloud business -- and it's going to be a wake-up call for rivals like Amazon Cloud Drive, Google Music Beta Digital Locker, Windows Live SkyDrive, Box.net, DropBox and SugarSync.

iCloud Beta was released for developers with a bang, featuring all the new Web apps for Mail, Calendar, Contacts, etc. It also comes with a "Find my iPhone" app that was earlier available as the MobileMe service, besides allowing users to view their iWork documents, such as Pages, Keynote and Numbers, that are stored in the cloud for any Apple device.

The service has already been lapped up by developers, and despite being in beta phase (read: work-in-progress) and access to the site reportedly being available only to existing MobileMe customers using Mac OS X Lion (according to PCMag, iOS device users haven't been lucky yet in accessing inside iCloud.com), it's posing a threat to its rivals.

The basic iCloud service, which gives you 5GB of storage space, is free. 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 from Apple for larger storage in the near future.

On first glance, iCloud may look pricey compared to its rivals -- especially Windows Live SkyDrive, which offers 25GB space for free and Amazon Cloud Drive, which offers additional 20GB for $20.

However, Apple fans can't complain, as by way of comparison MobileMe costs $99 annually for 20GB of storage. Apple will pull the plug on that service on June 30, 2012.

Moreover, music, apps, books, as well as your Photo Stream will not count against the free 5GB 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. And, that's good news to heavy iWork users.

However, there's a downside to iCloud. It can only offer limited storage days – 30 days. iCloud 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.

Nonetheless, the service has already been lapped up by the developers and despite being in beta phase (read: work-in-progress) and access to the site reportedly being available only to existing MobileMe customers using Mac OS X Lion (according to PCMAg http://www.pcmag.com/article2/0,2817,2390238,00.asp) iOS device users haven't been lucky yet in accessing inside iCloud.com) because like the App Store, iTunes is also now in iCloud. Which means any music or movie purchased is automatically backed up in iCloud and can be accessed using any Apple devices.

iCloud also enables users to have individual control over the music, apps and books and can also specify whether or not pushing the content should be limited to W-Fi connections only to save cellular bandwidth. iCloud also enables automatic wireless backups for iOS devices.

And, iCloud has iMatch. For just a flat $24.99 annual fee, iMatch will match the ripped songs in the user's library with 18 million+ songs in iTunes and upgrade them to higher quality 256kbps AAC DRM-free.

That's good news because Apple has stolen a march over its rivals by inking licensing deals with major music labels like EMI, Universal Music Group, Sony Music and Warner Music Group even as Google and Amazon struggle to come to an agreement with them.

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."

Start the slideshow to explore the top iCloud rivals. Let's see how they stack up against the newest kid on the block.

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