I think the revolutionary effect you are seeing can be better attributed to the fact that these populations have access to the Internet, especially through mobile phone. These people aren't leveraging the unique features of social media (the web of interpersonal relationships) so much as they are leveraging the ability to quickly get text, pictures, and video out of the country and onto servers hosted in countries sympathetic to the protestors. It just happens that Twitter and Facebook are currently the fastest ways to get something published and seen.