A new study found ground temperatures in Canada have risen significantly in recent years. Find this article here.
Jay Egg of Egg Geothermal in Florida writes in the Sept 2013 issue of Plumbing Engineer on some interesting approaches to ground coupling which were certainly new ideas to me. With geo-exchange (or 'groundsource'), we normally think of a flowing liquid in a closed loop of pipe inside the ground. This can be a regular pipe made of various materials, or it can be a completely sealed 'Heat Pipe' (look up heat pipes if you are not familiar with them http://en.wikipedia.org/wiki/Heat_pipe). However, there are other approaches of strong merit as well.
One such approach is the open-loop concept, in which one pumps water from the ground, harvests its thermal potential energy, and re-injects this water into the ground. This system has the significant advantage of reduced tendency for the local soil to drift in temperature, especially in dry periods.
Another approach is the standing column well (SCW). This I need to read more about.
A strong resource on ground temperatures in Canada: