Cooperation Works if Majority Can Punish Freeloaders

plasmid writes: "Some Swiss economists ran an investment game... they found that if the majority could punish freeloaders, cooperation flourished. I think this has implications for cooperative peer-to-peer systems and, to a lesser extent, for open source development. I'm so inspired I plan to go out an punish someone right now, as a matter of fact." I had just read this article the other day (go memepool), so this Nature piece seems oddly apropos.