Google's chief release engineer Jean-Baptiste Queru just announced via the Android Building group that version 4.1.2 of Android is being released to the Android Open Source Project (AOSP) today.
The release follows Android 4.1.1, which was the final version of Jelly Bean, and is marked as minor. The build number, which we spotted in the logs yesterday, is JZO54K, while the AOSP tags are android-4.1.2_r1 and jb-mr0-release.
It's also a good time to bring up the fact that the LG Nexus prototype that we saw yesterday was also running 4.1.2. Today's announcement seems to add further credibility to that story.