Some info on the game (Pulled from Neogaf forums, don't know the original source):
Another innovative example of the Game 3.0 vision is a brand-new community-based world called LittleBigPlanet. LittleBigPlanet starts with players learning about the powers of their chosen characters to interact physically with the environment. There are obstacles to explore, items to collect and puzzles to solve -- requiring community-based teamwork and brainpower. As players begin to explore, their creative skills grow and they will be ready to start creating and modifying their surroundings -- the first step to sharing them with the whole world. Ultimately, levels of the game will be user generated on a worldwide scale and will change everyday as players create, publish and share their own levels.
Users have the power to design, shape and build both objects and entire locations for others to play. Players can make their world as open or as secretive to explore as they like. When it's ready, they can invite anyone within the LittleBigPlanet universe to come and explore their "patch," or they can go and explore everybody else's.
Link to trailer: Link!
Sounds awesome to me! If I can create levels made of Rube Goldberg machines, I will want a PS3 just for this.