updated 01:30 pm EST, Tue February 19, 2013
New version does not appear to contain any other changes
Apple has updated its iOS platform to version 6.1.2 specifically to address a serious bug in the way it handles Exchange calendars. The problem, which first appeared in version 6.1, caused excessive logging and usage of resources on Microsoft Exchange 2010-based servers, and also ran down the battery and overtaxed affected iOS devices. Apple identified a fix on Valentine's Day but released it mid-day on Tuesday. The problem also affected Office 365's Online Exchange.
The bug revolved around using an Exchange-based calendar, which updates both the device and the main server during sync operations. According to reports, the sync operation would never complete, using increasing amounts of RAM and CPU on the iOS devices and filling up logs and tying up resources on the host server. The RAM and CPU usage caused iOS devices to heat up and drain the battery much more quickly.
The error was severe enough that AOL and other companies had to ask iOS 6.1 users to stop using Exchange calendar services until a solution was found. Microsoft's initial recommendation was to have administrators simply exclude v6.1 users or throttle their bandwidth allotment, but later offered a workaround option and said it was helping Apple find a solution.
The new version is available through iOS's built-in software update. Apple recommends that all Exchange email users download and install the update. It's not yet known if the update also fixes the lock screen bug identified in recent reports.