>>PaulHo+(OP)
I've been keeping an eye on heat pump water heaters for awhile, but right now they mostly make sense in warm climates. The big problem is they're still specialty products and marked up like crazy, but also they tend to use cheap components which makes them loud and prone to failure. If you run A/C for the majority of the year then they pay themselves back reasonably quick, barring early failure, but in colder climates they make your house work that much harder to keep the space warm.
The most optimistic hope is that the government mandate will force enough demand that manufacturers can enjoy some economies of scale and actually try to compete on price. I don't think this will happen anytime soon.