Both Mac's Mind and Austin Bay discuss Seymour Hersh's "expose" in the New Yorker.
What I think they both miss is that Mahmoud Ahamdinejad is the mullah's way of committing the geopolitical equivalent of "suicide by cop". Iran is a very young country (median age 24.8). Most of the youth do not care for the theocracy. The writing is clearly on the wall for where Iran is going to go barring a drastic event (say, a bunch of nukes turning Iran into a self-lighting parking lot).
The mullahs have decided that rather than see Iran go democratic, they will destroy it. It's an evil decision made by evil men who have decided that if they cannot have Iran, then nobody shall.