The Lights Out London campaign is trying to get Londoners to switch off their lights for one hour, 9-10pm, on the Summer Solstice, June 21st.

Sydney tried this for Earth Day 2007 and had a huge response. Initially only 65,000 people pledged to shut off their lights, but when the finally tally was in, 2.2 million Australians had answered the call to save energy. (via Inhabitat)

What do you think? Could New York handle an hour of voluntary blackout? Might make for some neat candlelight rooftop parties.