All right, time to pull back for a moment and play analyst.
There are two dimensions to this story: the election, and the reaction. The salient elements to the election are pretty straightforward: Mousavi was supposed to be either easily beaten by Ahmedinejad or be an unobjectionable "moderate" reformist. For whatever reason, the election moved in a much more vicious direction, and Mousavi started to become a lightning rod for the same sort of revolutionary imagery and attitudes that propelled a lot of the "color revolutions" over the past few years, and arguably the Obama campaign.
This clearly scared the Powers That Be into a panicked spate of election fraud, and they either didn't know or didn't care that they would get found out. At this point, though, it's pretty clear that they did get found out. There are still those hemming and hawing over whether or not the numbers might be legit, but they're being drowned out by those who apply both political knowledge and commons sense to come up with near-irrefutable evidence of fraud. All of these are known factors, or at least unknown things that can be known. In the intelligence biz, those latter things are what they mean when they talk about "secrets".
The other dimension is the reaction. That, in intelligence-speak, is a "mystery", because its full nature is unknown and can't be known yet. We've got the incredible riots in Tehran and, if Twitter can be believed, across the whole damned country. That came hand-in-hand with brutal police suppression and Iranian telecommunications getting nearly completely shut down.
But that's what happened. This reaction will continue for many days, weeks, and months to come. So the question is what sort of reactions are going to happen. It's a "mystery", as I said, so nobody can be 100% confident. But I'll break down what I expect.
First, the telecommunication blockade will be ineffective, and they will continue to get information out to the outside world. The twitterers and bloggers are getting through the blockade, and I imagine more will as time goes on, considering the relative age and expertise of the protesters vs. their censors.
Next: both the riots and crackdowns will get worse. The nature of this event is such that the government's illegitimacy cannot be denied. If the system permitted no election at all, that would almost be better; the people would be used to it and have to be converted to expect anything else. But all these people expected their votes to matter, and even Machiavelli knew that people who perceive a loss of assumed rights get really, really angry about it.
The opposition are scared and feel isolated, but since the wall will be ineffective, they'll be able to communicate with one another and the outside world. They'll be reminded that they are not alone.
Thirdly, the regime's future. This is a tougher call. This debacle is a huge blow to Khamenei. It has hurt the legitimacy of the Grand Ayatollah in the eyes of too many Iranians, and the way that it will be exploited by Iran's enemies (see next point) is going to cause a lot of Ayatollahs to become very cross indeed. Neither he nor Ahmedinejad will come out of this unscathed.
Whether they will come out of it at all is really hard to see. I don't expect a revolution; I don't think the elements are in place for it, especially from a strategic and tactical angle. But I don't completely discount it either, especially if it is accompanied by a "push from within" by those within the Assembly of Experts who are unhappy with the situation.
Finally, this is an unquestionable gift to Israel's right and American neoconservatives. It's hard to overstate just how much of a life-saver this is for that entire school of thought. Had the election happened honestly, whether or not Ahmedinejad would have won would have been almost immaterial. It still would have been "democratic" enough that the bright-line distinction between "Democratic West" and "Totalitarian Iran" that neoconservatives depend on would be hard to make, and neoliberal arguments about reform would have carried the day.
As it is, Iran looks like a banana republic. WORSE than a banana republic. They will easily be able to use this ridiculous farce to make the case that Iran's leaders have become completely unglued, and that Iran's people want America to come in and save them. That would be an absolute disaster, but it just became significantly more plausible thanks to this nonsense.
That may be the best argument for a revolution, or at least an ousting of the Ahmedinejad/Khamenei faction: because no matter how much damage it does, it'd be less than whatever the American neoconservatives would inflict.