We have gotten some tips from Bethesda now. They have said that they have been working hard on the first upcoming DLC that will be a timed exclusive to the Xbox 360. This add on will add new locations, quests, Features and more! They also said that they hope to officialy annouce it soon.

Sorce: http://www.egmnow.com/articles/news/skyrim-dlc-to-offer-new-locations-quests-features-and-more/