Excerpt:
Most foreign correspondents have been asked to leave Iran since young reformist voters took to the streets in Iran to protest what appears to be a fraudulent election. Thus, information about what is taken place in Tehran is being posted from Iranians by Twitter, Facebook and Youtube.
Twitter was apparently asked to change their scheduled maintenance time (when the site will be temporarily offline) to aid Iranians who want the rest of the world to understand what is happening there.
Adam Ostrow has more coverage of the Twitter angle at the website, "Mashable" The Social Media Guide."
People are uploading home made amateur videos hour by hour on YouTube. Here are a couple of examples.
If you are interested in helping spread information through twitter, the second video in the article gives instructions how to keep the Iranian government from discovering your tweets.