(Posted by John.)
I only have time for a brief post this weekend, so I'll direct your attention to this post at Green Car Congress: Pacific Gas & Electric has demonstrated a working vehicle-to-grid (V2G) capable hybrid car: a car whose batteries can be hooked up to the electrical grid and used to both charge and discharge, giving the grid a great deal more flexibility and potentially making it easier for large utilities to use more intermittent sources of power such as wind and solar.