Portal 2. You want it; we want it; your dog wants it. Have some new shots and concept art for it.
Game Informer has the full lot. You'll see some stuff previously released, but there's some stuff there that's very much new. Go give them a whizz.
Portal 2 is due out by the end of the year for Xbox 360, Mac and PC. Unlike the original, there's no PS3 version.