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.
BB reader Luke adds,
Also this twitter user is posting. They reckon the protests are largely peaceful and also guess at least hundreds of thousands are on the streets.
Link to Twitter search for hashtag "IranElection." Some Twitterers I'm following on this issue: @persiankiwi, @ johnperrybarlow , IranRiggedElect, @Pouyan. Here was a liveblog post over at HuffPo by Nico Putney. Here's a piece by Nasrin Alawi. Please add other resources you're following in the comments.