Looks like the X Prize Foundation is setting its sights on something a bit more down-to-earth (earth-y?). I think I'd like to see a good 100mpg car out of them than a new spacecraft, personally.

"The foundation billed the contest as independent and technology-neutral. It is open to teams from around the world that can design green vehicles that people want to buy and that meet market needs for price, size, capability, safety and performance."