This picture is amazing. But the picture itself isn't as amazing as the event. Over 2,000 people took off their clothes to contribute to Spencer Tunik's photography. For some puritanical reason, I don't think you'd get the same turnout in the US. In fact, there are probably laws against it. You can see some similar work he's done in the states here.
The question this forces me to ask myself: Would I take my clothes off in downtown Montreal if everyone else was doing it?