Hi Melissa, I'm sure that an essay could be written on this subject. Perhaps you could say something about where you're coming from in looking for this information?
I'll mention a couple key points. In LEED-NC, the main rating system, ground  source heat pumps would be a potential energy efficiency strategy under EAp2 and EAc1. LEED-NC doesn't have a credit specifically for GHG reductions, and the water efficiency credits cover technologies like toilets that consumer water, while heat pumps use water in a closed loop.
I'm not that familiar with where ground-source heat pumps are being used, but anecdotally I would say they're more common in heating climates.
I may be on the losing side of this battle, but I also think it's important to distinguish between geothermal energy, which uses heat from the Earth's mantle to make electricity and provide heat (as is done in Iceland, for example), and ground-source heat pumps, aka geoexchange, which use the Earth's surface as a place to extract or reject heat in a way that increases the efficiency of the system, but in which the Earth does not ADD any energy.