Look, behavior is motivation filtered through opportunity. So if you see people behaving in new ways, like with Wikipedia and whatnot, it’s very unlikely that their motivations have changed, because human nature doesn’t change that quickly. It’s quite likely that the opportunities have changed.
Clay Shirky, speaking with Daniel Pink about cognitive surplus and intrinsic motivation.
This was an eye-opener for me. If we really are entering an era in which the role of UX design is to encourage behavior change, then Shirky's view of behavior is important. The idea that we're providing opportunities—rather than trying to persuade or seduce—makes a lot of sense to me. It's a step in the direction of treating people like people rather than users.