I've already become a fan of the Genius feature in iTunes 8. Unfortunately, my computer is not typically where I listen to music. For me iTunes has always been more of a hub for organizing music (and other content) and syncing that music to other devices. I usually only end up playing music on my iPhone (while driving, running errands, working out) or on my Apple TV.
While it seems likely, the iPhone will gain access to the Genius capabilities with tomorrow's iPhone update much like the iPod Touch did earlier this week (I doubt I'll be a happy camper this weekend if that doesn't happen), there's been almost no mention of the feature in relation to the Apple TV. Given the effort it can take to browse the Apple TV's menus for specific music of any kind, mine is often playing song on shuffle of the entire library with the skip forward button frequently used to skip past anything that I (or the friends and family hanging out in my living room) aren't in the mood to hear.
Sure the Remote application for the iPhone/iPod Touch is a little easier to use for changing music selection than the standard Apple remote, but I still think a gathering of friends hanging out in your house is a perfect setting for Genius. Think about it - you're all hanging out listening to some tunes, eating pizza, playing poker (or some other game) and someone's new favorite song comes one and the group goes "can we hear more stuff like that?" - perfect situation for Genius. No menus, just a couple of clicks, and you barely have to look up and possibly give away any sign that you were just dealt pocket aces.
And Genius is the only feature that would needs to be added to the Apple TV. With support for HD TV shows, the Apple TV is probably the most important place for those shows to be purchased and played. Certainly, that's where I tend to buy TV shows or rent movies from the iTunes Store these days.
It doesn't seem like an Apple TV update is out of the question to support either of these features. The bigger questions are whether it will be free to all existing Apple TV owners or whether Apple will bundle it as part of an overall upgrade to the device. Personally, if they go that route, I'm hoping it won't be limited to only new models (again, I wouldn't be a happy camper) but I would be willing to consider paying $10 or so for such a software update for my more than year old Apple TV. The final big question is when will Apple get around to making updates available (hopefully very soon).