It is an interesting concept. Our kids have their water heater on a timer, for example. It heats the water overnight, with cheaper rates, and they seldom run out during the day.
It is more difficult for people our age and older, who cannot schedule particular activities after-hours.
For the frail or ill, those getting family, or paid professional caregiving during the daytime, they are unable to schedule their Activities of Daily Living (ADLS) at anything but during peak hours.
That said, in the recent mess of Hurricane Sandy, our Hydro crews are going to the US to help out those States involved in clean-ups. A big issue for NYC is the lack of electricity.
The hydro pole is put into place. Then the supports are drilled and wires attached. I wonder if their moms know what they do?!