This is being observed this year by turning off your lights for an hour, starting at 8:30 pm on March 31, 2012, local time. Australia has already done this- sorry I'm late posting this for our many members in Australia, New Zealand, and other locations where 8:30pm has already passed!
My father, my brother, and I participated (for two hours, actually). I didn't really care if it was tacky, trivial, or somehow ignored larger issues, though I think there's soooo much more we can do. We just sat outside and talked for a while. It was nice.