I put up a blog post about this topic:

http://gm-volt.com/2010/10/06/should-you-get-time-of-use-metering-for-your-electric-car/

I found that a TOU meter will actually increase my electric bill. This isn't true for everyplace in the country, especially California. But I think it's important for people to check with their utilities and analyze their electric use to see if it makes sense for them.

Also watch out for the flat rate package that some utilities are introducing, like Detroit Electric and their $40/month deal. Sure, that's far less than you'll pay for gas, but far more than you'll pay if you just stick with plain old single-rate metering.

Man, I am really spoiled in the Deep ("Dirty Coal") South, where we have 10 cent/kWh electricity.

I have no idea what my rate is, which I know is terrible. We have moved twice here in SoCal and both times when I signed up for electricity I checked the box that said, "Yes, charge me 10% more for my electricity but provide more of it from renewable sources."

We have a Rav4 Electric. When we installed the charger Southern California Edison added a time-of-use meter as a matter of course. They now want to take that meter out. I used an online tool at SCE.com and it said that I should have a time-of-use-meter.

We have solar panels (leased from Solar City). Our electric bill was nudging over $300 a month and now it is down to $60 a month. ($120 to lease the panels, but I would do it even if it were break even, I love technology.) Because we sell energy back during the day, purchasing most of our usage at night, we now have a time-of-use meter on the entire house. It is approximately 1/3 the price after 7pm. (So it drives me crazy when I come home in the middle of the day and my wife has the car plugged in.)

Colin, et al.:
SoCal Edison has a fairly detailed site here:
http://www.sce.com/PowerandEnvironment/PEV/
I have a lot of reading to do.
If anyone else has experience/guidance to offer regarding SoCal Edison, please offer it.
thanks