Just Dance. As detailed by the press release, the auditions will begin in France before moving to London and, eventually, the US. The game's Facebook page has all the details. [Update: That UK event is fine if you can get there, but in the U.S. branch of the contest, you can actually enter a video online! Check it out here.]
Before you get too excited, know that the official Joystiq dance team, Jamaretto, will be participating and -- against contest and federal regulations -- we'll be breaking out all our signature moves like the Grand Crunk Railroad, the Gogurt, the Sprained Cankle and the Spin Around Really Fast. So ... yeah. Bring it.