It is also worth noting that Mohammad Pahlavi (aka 'the Shah' and the person we backed after the coup) was a really, really heinous individual who did some incredibly nasty shit over a couple of decades as he clung to power. Like many revolutionaries of that period, the people who overthrew him had a lot of very legitimate grievances.
Furthermore, as most of the student leaders and politicians opposed to the Shah were leftists, the US continued to undermine efforts for them to organize (lest they side with the USSR). So that, when a popular uprising finally did occur, the clergy were the only group with sufficient organizational structure left that they could form a new administration...thus bringing us to today.
My understanding is that it was exactly the opposite: the Shah was too meek to assert himself and reign in his courtiers, some of whom were up to some very evil stuff. And of course, it didn't help that people really were after him (remember, he was the rightful emperor whom Mossadegh served; it really doesn't deserve to be called a coup when the emperor fires his Prime Minister, as was his constitutional right), and so his government felt justified in searching for people…out to overthrow him.
