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. … At both Digg and Wikipedia, small groups of users have outsized authority. In the case of Wikipedia, this authority is both organic and institutionalized. A small segment of highly active users author the majority of the site's content; there are also elected site administrators who have the power to protect pages, block the IP addresses of problem users, and otherwise regulate Wikipedia's operations. At Digg, active users have more of a de facto authority over the site's goings-on (though there are persistent rumors that the site has "secret moderators" who delete content). But officially speaking, while the site's algorithm seems to favor devoted users, no individual Digger has the power to unilaterally delete a post.

-Chris Wilson, "The Wisdom of the Chaperones," Slate