The next minor incremental update to the Android 4.2 codebase is rolling out to all Nexus devices right now. The update may address the widespread bluetooth A2DP audio streaming bug on the Nexus devices as well as few other minor issues.
Devices getting are the Nexus 4, Nexus 7, Nexus 10 & finally the Galaxy Nexus. Not much is known about this update but it bears the build name of JDQ39 and weights around 47.6MB in size. The changelog is expected to be released sometime later when Google updates the AOSP website. Users will very get a notification similar to this:
If not you can manually update by going to to Settings > About phone/tablet > Software updates.