Aside of that, iOS 5.1 brings new features like ability to delete images in your photo stream, camera shortcut on lock screen, Japanese language in Siri, improved face detection and battery life improvement.
You can utilize OTA update via your iOS devices, or using iTunes from your PC using manual update. And these are download links of iOS 5.1 firmware.
Any way the following are iOS devices that iOS 5.1 supports.
- iPad 1, iPad 2,
- iPhone 3GS, iPhone 4, iPhone 4S,
- iPod touch 3rd & 4th gen, and iPad 3.
- And also available for Apple TV 2 and Apple TV 3.