Xubuntu 12.04.4, the last point release for 12.04, has been released today along with the rest of the Ubuntu flavors. Users using Xubuntu 12.04 will be upgraded to 12.04.4 automatically along with normal upgrades.
The 12.04.4 point release brings in completely updated documentation that is also specifically targeted for 12.04. The complete release notes for this last point release can be found at https://wiki.ubuntu.com/PrecisePangolin/ReleaseNotes/Xubuntu.
The support window for Xubuntu 12.04 will end on April 2015. The Ubuntu core for 12.04 is supported until April 2017.