It occured to me this weekend that Chevy should incorporate some sort of ignition interlock or other form of warning into the Volt to prevent someone from acidentally driving away while the car is still plugged into the wall socket. This may sound silly, but people do drive away a gas stations with the hose still in the tank. I imagine that it will be much more common for Volt owners to forget to unplug and try to drive off with the charging cord still plugged in.
Yes, the vehicle should not be able to move if taking energy through the plug; however, GM should incorporate a passively rotating, tilting "socket", such that the inevitable hard tug on the cord doesn't bend the prongs. The vehicle may not move, but someone is going to trip on the cord, and you want the "socket" to smoothly disengage the cord without damage.
It seems to me that the details of how the power cord connects to the car is a really difficult design issue. The difficulty comes from the fact that it is done day after day, so little issues become big ones. One issue is the question of driving away while plugged in, as you cite. Presumably some sort of interlock can prevent that. Another is a poor connection. What to do here? Another is what to do in the rain (or snow or sleet or bitter cold). Another is how to allow one-handed operation (people often are carrying something else). Another is how to keep from scraping your knuckles while plugging in the car with one hand. Another is how to keep your extension cord from being stolen by your neighbor. All these are little niggling issues that have no glamour, but done day after day become really annoying. I hope some good engineering is going into this 'detail', as it not only can but will become 'one of those things' that encourages or totally repulses owners, and soon thereafter as word gets around, buyers.