The DARPA Grand Challenge is an annual race sponsored by the US Governemnt. The goal is to create a vehicle that can pilot itself through a desert course in the south-western United States.
The first race took place on March 13, 2004. Unfortunately none of the robots came close to finishing. Participants are expected to improve every year, as they have in many other robotics competitions.
The prize money for the first even was $1 million, which has now been bumped to $2 million for the October 8th, 2005 event.
Here's a list of teams competing.