The first DLC pack might be called "Dawnguard" and will be a timed exclusive for the Xbox 360.
http://www.egmnow.com/articles/news/...st-skyrim-dlc/
The 1.5 patch for the console versions is currently in certification process. The Steam patch for the PC version should be available by now.
http://www.egmnow.com/articles/news/...certification/