Here is a link to the European Hot Dry Rock project:
http://www.soultz.net/version-en.htm

They drilled three holes, two to get the water in and one out, but unfortunately one of the 'in' wells did not connect up - they hope when they do these things that the rock will fraction and allow the water to flow through, and so at the moment they look like getting half the power they had hoped for - similar problems led to the end of an earlier English HDR project.

The precise geology of the area is very important.

Geothermal from old oil wells could probably work great.

http://www.youtube.com/watch?v=qvQr7f_BJyQ

It works like this. the oil wells run dry and we tap those for there geothermal energy to power our electric vehicles and plug-in hybrids. kind of ironic that old oil wells could produce green and renewable energy for cars that would use electricity to create less pollution.