Google has started rolling out a new version of Android 4.2 to Galaxy Nexus, Nexus 7 and Nexus 10 devices according to reddit users who posted screenshots of the same. This is an OTA (over-the-air) update and you should receive notification about the same on your device. You can also check manually for the update by going to Settings –> About Phone –> Software updates.
The update supposedly addresses the Bluetooth A2DP audio streaming issue, Google promised the fix for this issue in the next version of Android 4.2 at the time of Android 4.2.1 release. According to Google the update improves performance and stability along with some more features and improvements, but it is not clear what is included in the update.
Via Android Police