I've been noticing retweets from Iran on my own Twitterlist. They do seem to be reaching an unusually diverse selection of people.
"Wagner James Au says,
Iranians around the world are making extraordinary use of Twitter and Twitter APIs to send updates and coordinate the uprising that now disputes Ahmadinejad's election. (Some background from Andrew Sullivan here) Last night Tweets from Iran seemed to go silent for several hours, apparently after Iranian government intervention, but protesters just used TwitterFall.com and other workarounds to keep the information stream going. (As one developer supporter put it, "Open APIs equal freedom.") The mainstream media has been tragically slow to cover what seems to be a major social upheaval fueled by Twitter. "