That's true, but in my scenerio the person in the little appartment doesn't need that pc. There's say a 2 ghz version of that core that runs cool enough to be passively cooled. At any rate, even apartments usually have a basement where all the mechanicals are located, I wouldn't necessarily want to leave my dual 10 ghz pc in the shared basement though
A nice side benefit of the central server is you could tie it into the other mechanical systems of the house.. for example you could use it's exhaust in a heat exchanger to preheat the water going to the water heater. I see lots of opportunities to do things like that.. like having 1 central very large, high efficiency halogen light provide all the general lighting for the home, transmitted through fiber optics. Again you can use it's waste heat for something constructive, while at the same time improving the efficiency of the HVAC by removing the heat output of the bulbs that used to be everywhere.