Vanilla, open-source Android available for 10-inch tablet on Sony GitHub
Like the Xperia Z before it, Sony has announced that it's bringing the Xperia Tablet Z into its version of the Android Open-Source Project (AOSP). The project brings the latest vanilla Android 4.2.2 Jelly Bean to the tablet, with the caveat that it's not "certified or intended for daily use," and many of the features from the shipping ROM will be missing.
You'll also need to do a bit of legwork yourself if you want to get AOSP up and running on your Xperia Tablet Z. The code is available on the Sony GitHub, just as it is for the Xperia Z, but you'll need to download and compile it yourself. So this is by no means a quick, easy fix to turn the Tablet Z into a Nexus-style device, but active development from Sony -- not to mention community developers -- could eventually make this a tablet of choice for Android hackers.
You'll find more technical details over on the official Sony blog, linked below. The Xperia Tablet Z is already available in some countries around the world. The Sony U.S. store is currently taking pre-orders, with an estimated ship date of May 24.
Source: Sony Blog