It's not really surprising that it's the twitter folks in Tehran and other cities who are involved. Nor is it surprising that they're proving instrumental in coordinating and maintaining contact. Every revolution in history, including the Chinese, depended on an educated middle class.
It is doubtful that the under-class is as alienated from the regime. No matter how bad the economy, Ahmadinejad's main domestic issue was providing welfare for the poor. The paramilitary Basij is likely recruited from the same people, and they are probably disproportionately represented in the Revolutionary Guards. Together, they enforce religious--and now political conformity.
This is the moment when other groups might begin to join the twitter rebels, groups beginning to realize how the regime has screwed them over, too.
Why would the regime blatantly falsify? Is it desperate to stop social change? Ahmadinejad is its bulldog to keep change at bay.
I wonder if Khamenei realized that he was unleashing such chaos, but his brazen falsification may have been an intentional statement saying: the regime can do whatever it wants. Ahmadinejad's re-election, he said, was a gift from God--(note: not the people). That's the kind of statement that foments rebellions, because he's claiming absolute power, and most people in the contemporary world won't stand for such claims, even if they crave authoritarian government (some peoples do). Falsification in front of everyone says that the regime really doesn't care what people think.
Iran may have a very effective security apparatus, but if a regime has only that, given modern techniques of organizing, then the revolutionaries have a chance--if some of the security apparatus defects.
Is the resistance US-inspired? I doubt it. An Iranian tweet last night said Obama did well by not coming out in favor--US support would unite Iran's repressive and nationalist forces.
But the uprising could be a gift to Obama either way: nuclear negotiations could prove easier even if Ahmadinejad prevails; the regime will need legitimacy.
Change is possible in Iran; how about the US?