Did you read our ModNation Racersreview? If so, you know that the game's Career mode was a big hit with us. Unlike most other kart racing games, United Front Games has crafted an actual story (with cinematics and voice acting!) to flesh out the Pleasantville-esque world of ModNation Racers. This trailer from PlayStation Blog highlights some of the more memorable events from the game's Career mode.
Don't forget -- the PSP version has the same story and cinematics as the PS3 version, and it also features the same multi-tiered objective system!