The only manufacture of a heat pump system I know of is these guys at Air Generate http://www.airgenerate.com/
There are new credits available for the 2009-2010 tax year for installing energy efficient products. Link
One of the credits is for efficient gas water heaters. Another is for electric heat pump water heaters. So far as I know, no major manufacturer makes a standalone, all-in-one heat pump water heater. I have seen heat pump add-ons available for standard electric water heaters, but have not seen a prepackaged kit (with both a storage tank and heat pump).
The problems I see are that this is a relatively untested technology, and that it requires that the water heater be in an open area for the heat pump to operate efficiently (or a vent to the outside). Also, they require a condensation drain, and it's likely that a heat pump will be noisier than a standard water heater (but not as loud as a forced-induction water heater).
In light of the tax credits, are any major manufacturers (e.g., Rheem, Bradford-White) planning to introduce a heat pump water heater?
The AirGenerate heat pump is a piggyback system--you supply the tank, feed the heat pump coil inside (and hope everything aligned correctly), and wire it up... It seems like a good concept, but I wish a major water heater manufacturer would offer a prepackaged, all-in-one system.
I'm not aware of any energy star qualified HPWH. Most of the systems I'm aware of are the Heat recovery units you use with an existing heat pump climate control system. These seem to be a more efficient solution, since the heat pump is already running and your just collecting the waste heat. In these systems part of the savings comes from increasing the efficieny of your existing heat pump. These are primarily used in the deep south with high AC demands. There are other units that work with geothermal heat pumps.
Most water heater manufacturer have an integrated heat pump water heater on the market. Some refer to them as a hybrid electric water heater - I guess that this is the hip name tag for a three decades old technology. :-) I think that 8 out of 10 heat pump water heaters are the GE Geospring hybrid water heaters made now in Louisville, Kentucky. I think the the Rheem HP50 and the AO Smith models are barely selling. I have not heard from anybody that they have one. I, myself, am contemplate an AirGenerate AirTap Hybrid water heater, since it can operate in heat pump mode down to 20 degrees Fahrenheit.
Unless ducted (and then, maybe not that useful), remember that any heat pump pulls heat from the area it is installed. This may be a bonus in the summer, aiding the a/c, but it will still cool things in the winter when you're paying to heat the house. Depending on where you can locate the thing, it may or may not be as efficient as indicated since space conditioning requirements can still add up. If it's in unconditioned space, then you'll likely have more standby losses in the winter, and the thing isn't as efficient since there is less heat to extract, not counting the potential risk of freezing the supply lines.
Now, if the thing can suck heat from an overheated area and discharge to an area you don't care about, that would be ideal, but most aren't configured that way.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014