Wirelessly posted (Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/530.17 (KHTML, like Gecko) Version/4.0 Safari/530.17)
NO, some users have been having an issue where AppleTV just suddenly disappears from the "Devices" list in iTunes, and it (obviously) won't play any streaming content until you restart iTunes on the computer and reset (unplug) AppleTV.
I've heard of the issue, but it only recently started happening to me.
I have 2 AppleTVs (one wired, one wireless on an AEBS) and it seems to happen to each unit randomly. Sometimes just one will drop, sometimes both.
It's a bit of a pain. I've heard changing the channel of your Wifi might help, but since one of mine is wired, I don't think that's my problem. I haven't had any time to sit and play with it though.
Hopefully this version of iTunes plays mice with the most recent AppleTV update.