Social networking sites, especially Facebook and Twitter, have been touted as catalysts for revolution and social change. While that's true, these sites have also been a big help to intelligence and police organizations. This can have fatal consequences in dictatorships, where the police and intel groups can use data gathering and analysis tools (developed for marketing via the Internet) to find people who are protesting or rebelling against the government. Even if these Facebook users are using codes and pseudonyms to remain hidden, the scanning and analysis tools can often uncover them. Twitter traffic can also be analyzed for useful information on who is doing what, and where they are.
Social networking sites are thus a double edged sword. They can be used to organize, inform and mobilize large groups. But in doing this, you provide the secret police a lot of information you would rather not share with them. Islamic terror groups advise their members to avoid social networking sites, but that has proved hard to enforce. Social networking was designed to be alluring, as well as useful, especially to the young. For young revolutionaries, this can be a fatal attraction.