Just make your own HTPC, you can get a decent Atom board for not much. Then you have a small pc behind your tv which can do a lot more than Apple TV and Google TV
And a lot more cumbersome too. I have a Mac Mini hooked up to my tv which is even more practical than a small Atom PC but even with XBMC and all, I just don't see it being a true TV replacement for non geeks anytime soon, and unless we have something that can truly replace the cable, I don't think people will bother with these additional boxes. I know many like their Apple TV, Boxee, Popcorn Hour, etc, but as Jobs has put it, it remains a "hobby" and a niche market for large players.