I got in this great discussion last week about how published psych studies may not necessarily generalize, primarily because the participant pool is typically comprised of undergrad students taking Psych 101. The example used was the Fundamental Attribution Error, where people over-emphasize personality attributes and de-emphasize situational factors.
In a separate discussion, Alessandro Acquisti forwarded this paper, which has one of the best titles I've seen: The Weirdest People in the World? Here, WEIRD stands for Western, Educated, Industrialized, Rich, and Democratic. The argument is essentially the same, that a lot of psych research is based on a narrow slice of the world population.