This is why a Chevy Volt could easily power your whole house in a blackout, if GM would include the small additional amount of hardware to allow for such a feature. Your car could take the place of a $10,000 whole house generator and I would bet the incremental cost for parts to do it on the Volt would be less than $500.
At a constant 65mph, your Volt's battery is putting out roughly 25kW. And most homes use 10kW or less instantaneous, and certainly much less on average.
It's cost prohibitive aftermarket, because a 300V inverter is, itself, expensive, and playing with 300V isn't for the faint of heart. But GM has the inverter essentially as part of the motor controller. Or with some added hardware, the battery charger could be an inverter as well. Heck, if they're truly working on Vehicle-to-Grid as they state, that prototype has all the functionality that's needed.
Just one more way to make the Volt that much more of a bargain for buyers.