I understand why you might want a tv on the wall, or a monitor thats basically being used as a tv, especially a nice big 30" one.
BUT
Why do you want an iMac on the wall?
How are you going to use it - are you going to sit on a chair beneath it or across the room from it, using a wireless keyboard and mouse perhaps.
Maybe this is Apple trying to replace the flat screen TV's being hung from every bedroom wall. That makes sense for a consumer product. Imagine your a parent of a teenager, they 'need' a TV & PC in their bedroom and they want a cool flat screen TV. Buy them an iMac and you've killed two birds with one stone. If they spend their money on a expensive flat screen TV they might opt to save of the PC and buy a cheap Dell.
Hopefully in this scenario well get an update to DVD Player and some Digital Media Centre PVR type software bundled.