It might not be the mysterious Android 4.2.2 version which we’ve seen running in the wild not so long ago but it is said to fix a couple of issues. A new source code has surfaced on AOSP (Android Open Source Project): android-4.2.1_r1.2. The build number is JOP40G and the changes don’t seem the include the Bluetooth fix mentioned by a Google employee, which will probably be the star of the 4.2.2 refresh.
However, improvements seem to fix some power management issues alongside introducing some tweaks to the way the EXT4 partition handles file creation. There’s no information yet on when exactly this update will be pushed out but when/if it will be, Nexus 4 users who had power-off problems after disconnecting the charger will have this issue hopefully fixed.