On Wikipedia's reliability

Via Media Channel

While any user can theoretically change anything, the site doesn't run completely wild. Volunteer administrators mediate debates and require contributors to provide external sources on contentious assertions. Paragraphs that draw excessive debate may be temporarily removed to special "discussion" areas, where opposing contributors negotiate and hammer out paragraphs in ways that will satisfy both sides.

The process inevitably turns up a wealth of interesting background material, if not definitive conclusions. Because of the combative, quasi-democratic vetting and editing process, the quality of the entries actually improves when the topics are controversial and the readership is broad. Opposing sides fight to ferret out inconsistencies on the other side, as reputations are built up from scratch on the site.