Hello!
I have posted links to the room reservation forms for our two hotel options in DC: http://wikimania2012.wikimedia.org/wiki/Accommodation.
The two hotels we have group deals with are the Dupont Circle Hotel and the State Plaza Hotel. The Dupont Circle is an incredibly cool hotel with everything a traveling Wikimedian could want. The State Plaza Hotel is not as awesome, but it is three blocks away from the venue and costs less. (It's still a good hotel, all things considered.) With both hotels, you are allowed to have a second person stay with you for no additional cost—that way, you can split the costs with someone.
We also have a sizable reservation at Hostelling International, but due to the many people receiving scholarships we cannot open that option up to the public right now.
We will be adding more options later, including more low-cost rooms as well as links to cheap hotels in the suburbs. I understand that cost is an issue for many attendees, so we are working to find accommodations that will work for everyone.
Regards, James Hare Coordinator, Wikimania 2012