I'm sorry, but I really don't have much respect for gimmicks like the upcoming Earth Hour, where we're all supposed to turn off our lights at 8 pm on March 29th. Yes, I know they mean well, and it won't do any harm. It won't do any good, either -- and that's the problem, because the people who participate somehow think it will.
Maybe it raises awareness, I don't know. But we didn't all become a big happy family after Hands Across America. If you aren't getting the message on global warming by now, you have ideological reasons for doing so.
The energy/GHG savings will, of course, be essentially nil. If every person on the planet participated, it'd be about 0.01%. Seeing as they only have about 40K people signed up so far, the savings will be on the order of 0.0000001%.
It emphasizes the wrong thing -- that the solution to climate change requires we regress to some pre-technology state. We don't need no light, we need better lights. We don't need to use less energy--energy makes us affluent, healthy, and happy--we need to use it more efficiency and from cleaner sources. Focus on that.
I'd rather everyone kept the lights on and spent an hour reading a good primer on global warming and its mitigation. Or wrote a letter to their Congressman advocating against new coal-fired power plants.