http://www.theregister.co.uk/2005/10...ality_problem/
Wikipedia co-founder Jimmy Wales has admitted that there are quality problems with some of the articles on wikipedia.
It seems to me that the strength of wikipedia (the fact that it can be updated by anyone) is also it's greatest weakness because there is no real peer review system in place.
Peer review is a system where fellow "experts" in a subject question what is published in papers, in an effort to refine those papers.