Here are some of the updates the iOS 5.1.1 brings, according to Apple:
– Improved reliability of the option for HDR for photos taken using the shortcut on the lock screen
– Fixes problems that could prevent the alternation between the 2G and 3G networks on the new iPad
– Solved problems connected to the AirPlay video playback in certain circumstances
– Improves reliability of synchronizing Safari bookmarks and Reading List
– Fixes a problem that sometimes causes the display to show the warning ‘Unable to purchase’ after the purchase is complete.
The full update can be downloaded either through iTunes, or the smaller delta update can be accessed directly on the iOS device through the Settings application. The software update is called “Build 9B206.”