You can now pre-order Invisible Handlebar's Audiosurf on Steam for $9.95 (there is a 10% discount for pre-orders). The game will be released on the 15th of February 2008, while a demo will be posted up on the same day. The official web site was also relaunched with a new look to celebrate the announcement.

This download contains the extra bonus of Valve's The Orange Box soundtrack to play with, which includes Portal's "Still Alive" song. (Gamasutra article)