I came across this article at CNN, "Charting the psychology of evil, decades after 'shock' experiment," which revisits Stanley Milgram's famous "shock" experiment. Professor Jerry Burger at Santa Clara University recently replicated Milgram's experiment with some tweaks to reflect updates in ethical standards for human subjects:
The new results correlate well with Milgram's: 70 percent of the 40 participants were willing to continue after 150 volts, compared with 82.5 percent in Milgram's study -- a difference that is not statistically significant, Burger said.
Still, some psychologists quoted in the same issue of American Psychologist questioned how comparable this study is to Milgram's, given the differences in methods.
My old post on this topic has some additional thoughts, "Evil and Ethics in the Workplace"