User blog comment:Lost Labyrinth/The Sims 3: Pets has been announced/@comment-2225748-20110603194435/@comment-26744861-20110603194754

They probably announced it because it was already leaked as The Sims 3: Unleashed.

Similar to Assassin's Creed Revelations, that was leaked so Ubisoft just came out with the offical announcement because everyone knew of it anyway.