Here's an interesting BBC article written by two psychologists detailing how their research speaks to recent events in Abu Ghirab and also complicates most earlier interpretations of the Zimbardo & Millgram experiments. These earlier interpretations essentially contend something like "if we all shared the same circumstances as the soldiers working the prison, we all would have ended up doing basically the same thing."
Certainly these newer studies don't invalidate the results of the Zimardo or Millgram experiments. What they do is caution us against reaching very broad and simplistic conclusions from the experiments. Unfortunately, answers to difficult problems are rarely simple and often times a nuanced picture or solution ends up being a closer approximation to the truth than one that is painted in grand, but broad strokes. I think Dr. J's reading of those experiment's significance is generally correct: "Basically what those experiments showed was that under certain conditions--primarily conditions that exploited people's trust and confidence in authority figures--some people might forgo their independent moral standards. The studies did not show that we all would do it, nor did they show that any of us could do it in a situation in which we had to make the independent decision to do so."
I need to give Dr. Johnson practically all the credit for the information contained in this blog post. If you want to read Dr. J's original blog post on torture, where this info came from,you can do so here: http://readmorewritemorethinkmorebemore.blogspot.com/2009/05/torture-101.html