The accuracy of Wikipedia
Much has been made of the accuracy of wikis - collaborative documents that has an open editing interface. Wikipedia is perhaps the most well-known wiki out there. It’s not 100% accurate, but what is? Other encyclopedias have errors too. Just with this one, they can be fixed. Who in their right mind would use any encyclopedia as a primary source anyway?
The best explanation of Wikipedia is a movie about how one article evolved. See the screencast here: http://weblog.infoworld.com/udell/gems/umlaut.html