Whether to buy an Apple TV has all sorts of other factors besides "when will it be updated next?"
I want to know whether Apple's serious about 99 cent TV shows, whether video rentals will come through, whether competitors will have more attractive alternatives like whether DirecTV will support TiVo HD, whether Apple will support true surround sound, HD, and on and on. It's not a question of "do I upgrade my computer now or later"; it's a whole constellation of things not easily distilled on the buyer's guide.