Been browsing through the AppleTV forum and to be honest if your budget can stretch to it I would use a Mini/old Laptop as a media hub over a ATV, or at least thats my conclusion.
I have an old Macbook sitting behind my TV running 24x7 using PS3 MediaServer and network linked to an external USB drive plugged into my Apple Airport Extreme which holds all my Photo, movie, music (iTunes) files etc.
It also runs the full OSX version of BBC iPlayer (so I can DOWNLOAD shows (living abroad with a crappy broadband makes downloading essential, no way will streaming work). I also of course have my iTunes etc all available locally as well.
Benefits over ATV - I can watch any format I like (with either VLC locally or PS3 MediaServer through my PS3),
I can watch iPlayer HD without any weird DRM removal nonesense,
I can still use PLEX / XBMC or anything else available without any hacks etc.
How do I control all this?
iPlayer and general use = Mobile Mouse Pro for iPhone
VLC - VLC Remote for iPhone (don't actually need to use VLC as I play all movies through the PS3 using PS3 MediaServer on the Macbook)
PLEX - PLEX Mobile for iPhone (I don't use PLEX but I would use this if I did)
XBMC - Same as above but XBMC version - ditto don't use XBMC
Other content - my PS3 Remote. (Photo's, Music, Movie files - all handled with PS3 MediaServer).
I use AirServer so I can still use airplay to send files from my iPhone etc to the Macbook so no loss of functionality there either...
I don't see any reason at all for an ATV, you need a PC somewhere in the house switched on anyway to stream anything to the ATV, you can't do iPlayer etc, can't play all movies unless they are encoded in a format it supports, have to hack it (which you can't do with ATV3 anyway) to get it to run Plex etc and it has no storage so is totally reliant on either Broadband to see the Cloud or for a Mac to be switched on also for it to stream from...
it's just (FAR) too restrictive IMO..