thatgamecompany, the studio responsible for PSN titles Flower and Flow, have had their next game leaked a little early. Ah well. It still looks interesting!
The game is called Journey, and in stark contrast to the solitary focus of their last two games, this is an "online adventure experience", where players are out to explore an alien world. The multiplayer aspect comes from the fact you run into other explorers along the way, and each interaction between players "re-shapes the experience".
It's due for release on the PS3 sometime in 2011.