It is difficult to know now, while this is all happening, what is more significant in the prevalence of mobile phones and use of social networking: whether it's mobilizing the masses or getting the message out to the outside world.
Regardless, scores of videos are circulating in Iran, many taken by mobile phone or shaky hand-held cameras, like this footage above of a brutal beating at the hands of police.
Here is another video, allegedly taken this morning at a Tehran hospital where doctors and nurses were protesting deaths at the rally last night.
The problem for foreign journalists and news organizations, most facing reporting restrictions, is how to judge whether footage is what it purports to be. With the ubiquity of user-generated content, that's increasingly a problem. Where is the footage from? Who shot it? When was it taken?
Those questions aside, the footage has become a crucial part of the story (and that, we think, is a good justification for showing it). It is, after all, what Iranians are sharing on their mobile phones, on their laptops. It is what is fueling their anger and fear.
Just as it is the perception of electoral fraud -- rather than whether or not it really happened -- which is most important right now, it is the perception of brutality -- and that isn't to say it isn't real -- which is causing Iranians to take to the streets in droves.