I don't even know if hybrid heat pumps would qualify to be on green building talk, but, does anyone know anything about them?  Particularly if geothermal heating systems are out of reach for us right now????

It really depends on your climate and electric & gas/propane/fuel rates. A geothermal heat pump will definitely be more efficient than hybrid, but they do have the higher initial investment.

One thing to really consider, though, is that with air source heat pumps, the compressor won't last as long as geothermal because it operates in harsher conditions.