The development version of the upcoming Android 4.2.2 update for Xperia Z has leaked online. Posted by known XDA developer DoomLord, Xperia Z 10.3.A.0.407 firmware was meant for developer devices, but he has tweaked it to work on any Xperia Z smartphone.
Being a test release, it does not pack all the features that will be the part of final release and also bugs are common for such releases but if you are still feeling adventurous. You can head over to this XDA thread and download it.
You will need unlocked bootloader to flash this build, which can be easily done by going to Sony’s developer site and following the instructions. Flashing instructions are available at the XDA thread.
There is still no word on when Sony is going to officially release the update but considering the fact it is in development, it should be arriving in a month or so.
Here are some screenshots from this leaked Android 4.2.2 firmware: