Much of the virtual ink is devoted to describing myriad small fixes. That said, there are a couple of interesting nuggets related to the new Artificer class that was added to the game back in September. The steampunk ranged damage-dealer is now able to access the Sneak feat at level 1, and he's also able to revive dead Iron Defenders (even if said Iron Defenders are in another instance).
Turbine has also adjusted DDO's user interface based on player feedback, and the changes are most notable when you're viewing party vitals. Head to the DDO compendium for the complete list of updates.