iOS 5 is compatible with the iPhone 4, iPhone 3GS, iPad and iPad 2, along with the third- and fourth-gen iPod touch. iOS 5 will also be preloaded on the new iPhone 4S, Apple’s fifth-gen smartphone that goes on sale this Friday. All iOS 5 users as well as those running OS X Lion on their Macs will get 5GB of free iCloud storage, with more available at a fee. iCloud is Apple’s new synchronization and backup system that promises to deliver your music and documents across all devices.
Source: https://thehackernews.com/2011/10/apple-ios-5-released.html