Earlier today, Google started pushing some new open source code to AOSP (Android Open Source Project) marked with 2 new tags: android-4.2.2_r1.1 and android-4.2.2_r1.2. The build number corresponding to the 4.2.2_r1.2 release is JDQ39E.
The dates you see here are commit dates, not dates the commits were made public (which is today, April 17th 2013)
After weeding out the changes from the commit logs, it looks like all of them are, as expected, very minor. We've seen these _r1.X releases before, and the last one didn't fix much at all.
Here are the aforementioned changes between 4.2.2's tags 4.2.2_r1 (JDQ39) and 4.2.2_r1.2 (JDQ39E).