Esquire magazine tried a fascinating experiment - they had a writer post an article (with mistakes, typos, etc) to WikiPedia, and then solicited the audience to fix it. The results:

According to the Wikipedia page for Jacobs' story, the article was edited 224 times in the first 24 hours after Jacobs posted it, and another 149 times in the next 24 hours.

The final draft, which was locked on Sept. 23 to protect it from further edits, reflects the efforts of the many users who worked on it.

Here's the entire history of the effort - it really demonstrates the value of collaborative editing. The interesting thing about Wikipedia is how much it was pooh poohed by people in the beginning - the thinking was, if anyone can edit, everyone will edit - and trolls would end up owning the site. Something else entirely has happened, and it's now an extremely useful resource - I use it when I'm looking up historical references all the time. For instance - I had the History Channel on while I was cleaning my kitchen floor this morning, and heard the tail end of something about the Knights of Malta. Well - Wikipedia filled it in for me.