Apple officially announced iCloud, the company's long-rumored online data-storage service, at today's Worldwide Developers Conference. The service will allow users to store up to 5GB worth of documents, photos, and other information in "the cloud" for free, and it will sync that data to the customer's Macs, PCs,iPads, and iPhones. An optional service, iTunes in the Cloud, is free if all your music comes from Apple's iTunes store; storage of non-iTunes music will cost $24.99 a year.

According to the company's announcement, iCloud will automatically sync iPhone and iPad apps, as well as Apple's e-mail and calendar programs. Similar functionality was previously available to users of Apple's $99-per-year MobileMe service, which will be replaced by iCloud.

Apple CEO Steve Jobs said the service "stores your content and pushes it to all of your devices, and it's integrated with all your apps"--though at this point it's unclear how many non-Apple applications the service will integrate with. Microsoft Outlook is listed as an option for address-book syncing on Apple's website; MobileMe also worked with Outlook's mail and calendar modules.

The service's tight integration with the iPhone and iPad may give iCloud an edge over competing cloud-storage services, which include Microsoft Live Mesh (also free for 5GB of data storage) and Dropbox (free for 2GB). The cloud-based iTunes service, which matches your music with songs in the company's online database, provides unlimited storage for music that can be matched; any unmatched songs--up to a 25,000-song limit--are uploaded. Apple cited Amazon's cloud-based music service, Cloud Drive, as a key competitor and noted that storing 20,000 songs with Amazon would cost $200 a year.

The full iCloud service will be available this fall, as part of Apple's planned iOS 5 upgrade. A beta version of iTunes in the Cloud is available now.

Apple - iCloud - The new way to store and access your content. [Official site]