Today Apple announced (along with “The New iPad” and new Apple TV) that iOS 5.1 would be available for existing iOS devices.
Well the time has come, you can grab out now and the changes are thus,
• Japanese language support for Siri (availability may be limited during initial rollout)
• Photos can now be deleted from Photo Stream
• Camera shortcut now always visible on Lock Screen for iPhone 4S, iPhone 4, iPhone 3GS and iPod touch (4th generation)
• Camera face detection now highlights all detected faces
• Redesigned Camera app for iPad
• Genius Mixes and Genius playlists for iTunes Match subscribers
• Audio for TV programmes and films on iPad optimised to sound louder and clearer
• Podcast controls for playback speed and a 30-second rewind for iPad
• Addresses bugs affecting battery life
• Fixes an issue that occasionally caused audio to drop for outgoing calls
Go grab it now via Software Update on your iDevice or Via iTunes.