A recent Slate article describes the reality behind user-generated content champions such as Wikipedia and Digg.
Social-media sites like Wikipedia and Digg are celebrated as shining examples of Web democracy, places built by millions of Web users who all act as writers, editors, and voters. In reality, a small number of people are running the show. According to researchers in Palo Alto, 1 percent of Wikipedia users are responsible for about half of the site’s edits. The site also deploys bots—supervised by a special caste of devoted users—that help standardize format, prevent vandalism, and root out folks who flood the site with obscenities. This is not the wisdom of the crowd. This is the wisdom of the chaperones.
Why is the view presented in this article important to you? If you are touting sites like Wikipedia as proof of a social media utopia and someone (say, a Luddite-type administrator) confronts you with data like this, it is important that you have done your homework. Seek better examples for your arguments. They do exist.