Here in Canada, I think of Facebook as an interesting way to keep in touch with family and friends, nothing more. It’s just one of a number of social media that I use. However, for the government of Iran, Facebook is seen as a serious threat, as shown in this article: Iran blocks access to Facebook from The Globe and Mail.
I am not sure how successful this will be. I recall James Fallows writing that Iranians were using the same technology that the Chinese were using to get around the Great Firewall of China. I suspect that this blocking of access will be more of a slow down than a stoppage of use of Facebook in Iran.
Regardless, it just shows you that Facebook is more than throwing sheep and sharing pictures and other such silliness that some take it to be. For some, it can be a powerful means of organization and communication.