Geothermal heat pump, planning head?

What do people think about this, especially if used with wind energy?

http://en.wikipedia.org/wiki/Geothermal_heat_pump

I was thinking that maybe as opposed to in the city, a bunch of single homes using separate ones, it might make more senses to bury one much deeper, and large, for say a block of houses.

I love them. Have only installed one and priced another that didnt get built. There are MANY variables that go into their selection, performance and appropriateness. Ironically, the more efficient the structure, the longer the payback. So they tend to make financial sense for big, inefficient homes or existing ones that have a good opportunity to change out the existing heating/cooling. In general, for small, efficient homes its better to spend the extra money on additional Building Envelope improvements.