There were a couple of reasons that many Motorola Xoom owners, myself included, were concerned we may not see Android 4.2 on our devices any time soon. First, Google decided to drop both the Xoom and Nexus S from the Android Open Source Project—effectively leaving them to live out their final days on Android 4.1, in official capacity at least. There were also concerns about the size of the /system partition. Obviously as the Android operating system evolves, ROMs become larger and begin to approach the limits of system space available on some older devices. All that is now irrelevant though thanks to those stalwarts of Xoom development, Team EOS.
EOS4 Nightlies are based on Android 4.2, and will hopefully, in time, bring the full 4.2 experience to the now somewhat aged Xoom. At the moment, there are still bugs to be ironed out, and some of the newer features are yet to be implemented. These are, after all, nightly builds. However given the track record of Team EOS, you can rest assured that things will only keep getting better. On the whole, things are looking good, but make sure to check the thread so you know what to expect. At the moment, these builds are only for the WiFi only Xoom, the Wingray.