"In August, video game retailer Gamestop posted product entries for Sonic Riders: Zero Gravity for the Playstation 2 and Wii, set for release on February 1st, 2008; they were both removed a few days later." - Wiki
More screenshots here
I've never played Sonic Riders before, but watching the trailer it reminded me of F-Zero, and the graphics looked great! I'm gonna keep an eye out for this one!