Apple has just released iOS 5.1.1. for iPad, iPod touch, and iPhone, download from iTunes by connecting your iDevice to your computer or use Software update on your device.
The update includes various bug fixes and improvements including:
-Improves reliability of using HDR option for photos taken using the Lock Screen shortcut
-Addresses bugs that could prevent the new iPad from switching between 2G and 3G networks
-Fixes bugs that affected AirPlay video playback in some circumstances
-Improved reliability for syncing Safari bookmarks and Reading List
-Fixes an issue where ‘Unable to purchase’ alert could be displayed after successful purchase