Mahmoud Ahmadinejad won the 2009 Iranian presidential election with 62.63% of the popular vote. At least, that's what the "official" results show. Mir-Hossein Mousavi will tell you he had 62.63% of the popular vote.
Thousands gathered in protest, and the Iranian government responded by restricting all journalists working for foreign news organizations from reporting on the streets of Tehran. With the mainstream media out of the way, the citizens became journalists, reporting from the streets via Twitter, on Facebook and blogs. It was a corrupt government vs. web savvy citizens seeking freedom and democracy and Twitter emerged as a place to plan protests, share information and report to the rest of us what was happening on the streets of Iran.
Here's Andrew Sullivan writing for The Atlantic's blog:
I have to say my skepticism about this new medium has now disappeared. Without it, one wonders if all this could have happened. A reader notes a few facts:
Ahmadinejad's and Khamenei's websites were taken down yesterday - I saw the latter go down within a couple of minutes because of a DDOS attack organised via Twitter. @StopAhmadi is a good source for tweets on this. The other important use of Twitter has been distribution of proxy addresses via Twitter. This would be how most video and pictures of today's rally have gotten out.
Technology has not just made the world more dangerous; it has also enabled freedom to keep one small step in front of tyranny and lies. One thing you can do is use Twitter to fight the regime yourself. Help bring these fascist bastards down at the end of your modem.
It's not Twitter's revolution, the revolution belongs to the people of Iran. But it is Twitter's coming out party, enabling Iranians to seek what we take for granted. They are tweeting for freedom.