Take with your daily pinch of salt. Actually, make that the whole shaker. A load of details on Team ICO's new project were revealed on NeoGAF and have apparantly been taken from GameInformer's next issue. What the rumour says is that the game (titled The Last Canyon) will be set in a desert and that players will control the protagonist who uses a glider to explore canyons for "something". Kind of what Nausicaa did in the critically acclaimed Studio Ghibli film, Nausicaa of the Valley of the Wind.
The rumour has been debunked by a few on NeoGAF and some people have their doubts. We'll know if it's true or not when the next issue of GameInformer hits the US in a few days time.
Others reporting: IGN
Update: Seems this isn't in the latest issue of Game Informer after all (and one of the Game Informer guys on the GAF forum said so too) so this is now being labelled as false.