The Technology

Similar to that of a standard hybrid electric vehicle (like the Toyota Prius) but with the added ability to plug the vehicle in to an outlet so the internal batteries can be recharged without the power of the combustion engine.

The Possibilities

Beneficial in reducing fuel consumption and emissions. The real innovation here is the possibility for the vehicle to provide backup power for a home or even assist in regulating electric grid frequency. Connection to the grid gives the vehicle owner the ability to offset their electricity costs.

The Challenges

As with conventional hybrids there is a cost premium involved here. Would also require a special plug (something like a clothes dryer plug) installed in the garage which is not a standard for home construction these days.

The Outlook

Its hard to say as production versions of these types of vehicles are still a couple of years away. Technology changes fast and new innovations (like all electric vehicles) could make the plug-in hybrid obsolete before it gets to market.

Research Links

Wikipedia
CalCars
Plug In America