Loving this! The PlugShare iPhone app just launched on Monday.
The app allows electric vehicle users to find people who have offered the electrical outlets in their garages up as charging stations. There is no cost to the EV owner, though the website says that the cost is minimal, anyway - it costs $0.15/hour to charge an EV in your garage.
The New York Times suggests that we think of PlugShare as a combination of FaceBook and Foursquare, the location-based service, for electric car owners and their supporters.
Here's a quick "how stuff works" summary from CBS:
For more background check out the founders' profiles here.