I voted 'indifference' only due to the fact, I generally switch off all lights around the house and where possible all bulbs have been converted to those energy efficient ones. I don't need some 'earth hour' to inform me of the benefits of what less power consumption means.....unfortunately I guess some do.
If anything they should be targetting big dept or grocery chains.
As for the idea of turning street lights off, I like the idea, but it would also be an open invitation to crime, not just burglaries, but also sexual attacks.
Maybe they deliberately timed it for near full moon so things would still be 'bright' for those going outside at night.