Apple has published a support article letting users know that an iOS 6.1 bug fix is coming that will correct Exchange server issues users have been having. In the support article Apple details the symptoms of the bug:
When you respond to an exception to a recurring calendar event with a Microsoft Exchange account on a device running iOS 6.1, the device may begin to generate excessive communication with Microsoft Exchange Server. You may notice increased network activity or reduced battery life on the iOS device. This extra network activity will be shown in the logs on Exchange Server and it may lead to the server blocking the iOS device. This can occur with iOS 6.1 and Microsoft Exchange 2
