V2G (Vehicle to Grid) is a great idea - in concept.
The trouble is that it's pretty tough to get anybody to do anything unless you give them a very good reason to (government money for example)
Lot's of small distributed energy is much better than central power in terms of reliability.
Personally, I am still planning on rigging up my electric car to be able to act as a rather large UPS.
Plug my car in to the house to charge. When there's a blackout, plug my house into the car to run the fridge and things!
