Xubuntu 12.04.1 has been released today along with the rest of the Ubuntu flavors. This means everybody on 10.04 are able to upgrade to 12.04.1 at their convenience. Users on 10.04 should get an upgrade notification when booting their systems up the next time.
Users using Xubuntu 12.04 will be upgraded to 12.04.1 automatically along with normal upgrades.