Plug-in hybrids could increase grid reliability?

There have been some questions regarding how a massive fleet of plug-in hybrid vehicles might affect the power grid. While most studies seem to indicate there wouldn't be any serious problems, other studies actually demonstrate that plug-in hybrids might actually make the power grid more reliable, especially during peak hours.

"In addition, during the 90 percent of the time that most vehicles are sitting parked, electric-drive cars could actually supply power to the electric grid through a concept known as "vehicle to grid" technology or V2G for short. The V2G concept envisions the use of a bidirectional charger that allows electricity to flow into a vehicle's battery for charging, or lets stored electricity in the battery flow back onto the power grid. This could increase grid reliability and generate hundreds of dollars of revenue per year for hybrid owners."

(Source: Christian Science Monitor)