Kinohi asks in the comments:
Interesting numbers, but is there anything out there that gives us some sense of *how* the election was stolen so dramatically? Were there election observers in Iran? Who was in charge of local elections? Until we get a better account of how this was done, these numbers will be meaningless.I'm not prepared to answer that question except to say that the prevailing theory seems to be that votes were not legitimately counted at all—Ahmadinejad was simply declared the overwhelming winner by official state agencies after an extralegally brief period of time.
But there is more information coming out about the numbers that provides more context. Two posts from Nate Silver's FiveThirtyEight.com look at the numbers in more depth: first, what are apparently the official numbers from the Iranian government, including breakdown by province, and second a post from Nate's coblogger Renard Sexton charting statistical irregularities in this election against recent Iranian electoral history.
Matt Yglesias takes up the point Vu has been making in the comments, that late polls showed Ahmadinejad winning, and adds this important caveat:
That said, Juan Cole raises a hugely important point of interpretation. Ballen and Doherty talk about how their mid-May poll showed Ahmadenijad with a 2-1 lead, about what the official results show. But they don’t mention the specific numbers. According to Professor Cole, “It found that the level of support for the incumbent was 34%, with Mousavi at 14%.” That seems like a 34-14 is very different from an official result in which Ahmadenijad’s support was in the sixties. In the domestic American context if you had an incumbent polling at 34 percent, you’d say he was in huge trouble no matter how badly his opponent was doing.Ayatollah Khamenei has apparently pulled back from his proclamation of a "divine assessment"; he has now ordered an investigation into the results.
(Picture via the WSJ slide show. The image is of a pro-Ahmadinejad rally; I picked it because it is striking and because it reflects the extent to which both sides are rapidly becoming radicalized.)