That's an interesting observation (is it really true?) since you can find a good number of posts from Apple TV users who claim that the Apple TV can't even display 720p reliably (that is, without the TV experiencing random stutters). No doubt, the Apple TV 2 will accept 1080p sources right now (just as on my iPad) but I've read a number of reports from users who say that while 1080p will decode it won't play flawlessly.
Frankly, I don't expect support for 1080p playback on the Apple TV until next year, and that will require upgraded hardware (i.e. Apple TV 3, using a dual-core ARM9 CPU/GPU). That is probably when Apple will finally get serious about apps on the Apple TV -- right now I think they are too busy with the iPad and iPhone to be worried about the Apple TV. However, with just about every other TV platform supporting apps I think Apple will eventually be forced to do the same. Although AirPlay will become a great feature as soon as the content providers begin to support it (or more correctly, if they decide to support it -- not all will enable AirPlay because of licensing restrictions), I really believe that apps will need to come directly to the Apple TV. If apps don't come within the next year then I'd say that the Apple TV is going to fall prey to the smart TVs.