TIME magazine writes about the prominent role Twitter is playing:
"Twitter [is] practically ideal for a mass protest movement, both very easy for the average citizen to use and very hard for any central authority to control. The same might be true of e-mail and Facebook, but those media aren't public. They don't broadcast, as Twitter does. On June 13, when protests started to escalate, and the Iranian government moved to suppress dissent both on- and off-line, the Twitterverse exploded with tweets from people who weren't having it, both in English and in Farsi. While the front pages of Iranian newspapers were full of blank space where censors had whited-out news stories, Twitter was delivering information from street level, in real time:
Woman says ppl knocking on her door 2 AM saying they were intelligence agents, took her daughter
Ashora platoons now moving from valiasr toward National Tv staion. mousavi's supporters are already there. my father is out there!
we hear 1dead in shiraz, livefire used in other cities RT
As is so often the case in the media world, Twitter's strengths are also its weaknesses. The vast body of information about current events in Iran that circulates on Twitter is chaotic, subjective and totally unverifiable. It's impossible to authenticate sources."
During Hurricane Katrina, the formal news media itself circulated some horrific stories about events in the Superdome in that were later found to be untrue. With the media restricted in Iran, bottom-up, peer-to-peer networks have become the prime source of information. This factor adds additional complexity and volatility to crisis situations.
For more perspective on Twitter and the protests in Iran, read:
The Irony of Iran's Twitter Revolution (http://www.gauravonomics.com/blog/the-irony-of-irans-twitter-revolution/)