Supported Devices:

iPhone:
iPhone 3GS
iPhone 4
iPhone 4S

iPod  Touch:
iPod Touch 3rd Generation
iPod Touch 4th Generation

iPad:
iPad 1st Generation
iPad 2
iPad 3

Initial Release: 5.0 (October 12 2011)
Latest Release: 5.1.1 (May 25 2012)

New features:
- Newstand
- Reminders
- New Music and Video app for iPhone and iPad
- Notification Center
- iMessage
- Camera shortcut on Lock Screen
- 4G LTE support (iPad 3 only)
- Siri (iPhone 4S only)
- Accessibility Features
- iCloud