Aaron Swartz has been taking a closer look at Wales' claims that Wikipedia is being written by a small group of people.
When you put it all together, the story become clear: an outsider makes one edit to add a chunk of information, then insiders make several edits tweaking and reformatting it. In addition, insiders rack up thousands of edits doing things like changing the name of a category across the entire site — the kind of thing only insiders deeply care about. As a result, insiders account for the vast majority of the edits. But it’s the outsiders who provide nearly all of the content.
I think this enforces the idea that any good user driven site requires both good gardeners, and a mass of casual contributors who aren't experts in the workings of the site, but contributes with some factoids that works as seeding for good content. We see the same trend on iusethis, where some user creates an app entry, which is improved upon by others, and maintained by the group as a whole. I still believe we have some way to go in clarifying and giving power to the site gardeners tho, at the moment, we do too much of this work. Delegating this to our power-users would be doubly beneficial, as it would empower them, and free us up to spend even more energy on improving the site.