Apple have issues iOS 6.1.2 for the iPhone. The update fixes the Exchange bug that was hitting iPhone users syncing up calendars. The bug cause increased network activity and reduce battery life and Apple say this update resolves that problem.
The update is applicable to the following devices:
- The uiPhone 3GS and later
- iPad 2 and later
- iPod touch 4th generation and later
About iOS 6.1.2 Software Update
Fixes an Exchange calendar bug that could result in increased network activity and reduced battery life.