As Andy "Macian" Donaldson reported on Facebook, this years Wednesday party will take place at The Wizarding World of Harry Potter.
The park is brand new, it opened last June, but already during Lotusphere 2010 I blogged about the park as a potential venue for the 2011 party.
John Head just visited the park in late December, and gave a good review on Twitter. He especially recommended the butter beer, which just the other day sold it´s one millionth serving.
Update:As Andy clarified, he got the info fromepisode33of This Week in Lotus.