The Last Guardian was first announced in 2009, and has since dropped off the face the of the earth. However, the game is still very much alive, according to Sony.
The developer, speaking at the Tokyo Games Show, professes the game's continued existence: "I give you my word that it exists. We are working on it." He did, however, wish to go unamed.
The reason for the games lack of presence at this year's TGS is, acorrding to this same developer, that Sony don't wish to hype up games that are no close to release.
Only time will tell if this game is indeed still alive.