I have written previously on this issue (oddly, that was also a March 31st) and in that discussion observed that the likely cost to the environment to produce candles, t-shirts and all other manner of supporters' paraphernalia was far in excess of the gains achieved by turning off a couple of light bulbs (but not the TV - how else will they know what everyone else is doing?).
However, this kind of event is symptomatic of a wider malaise.
We are proudly able to feel good about ourselves for 'liking' a protest page on Facebook. The best part is that no more is required of us. We don't actually have to 'put it out there' by moving away from the computer and being seen in public as supporting the actual movement.
Online petitions are the same - total waste of a good point that they are, the signers may happily tell all and sundry the extent of their involvement in the issue, but there's little the targeted person or organisation should do about them. After-all, 99% of the signers will have completely forgotten about the cause within a week.
But everyone's voice did count (for what, it's hard to tell!).
After dark, the warm glow of smug self-satisfaction should keep everyone in the room fully illuminated this evening! There's a reason Earth Hour happens so close to April Fools' day.