You should read this article by Larry Sanger, one of the founders of Wikipedia who has since left the project. He calls for greater respect for experts and less tolerance towards trolls:

Nevertheless, everyone familiar with Wikipedia can now see the power of the basic Wikipedia idea and the crying need to get more experts on board and a publicly credible review process in place (so that there is a subset of “approved” articles–not a heavy-handed, complicated process, of course). The only way Wikipedia can achieve these things is to jettison its anti-elitism and to moderate its openness to trolls and fools; but it will almost certainly not do these things.

This is one of the things that bugs me about Wikipedia as well, and why I don’t use it for anything that really care a lot about getting right. Some of the articles are slipshod and others are misleading. If I know nothing about a topic (statistical physics, for example), I’m not going to look on Wikipedia to find out. However, if I wanted to know around when Abelard lived, I could look it up there and be reasonably sure it’s correct, or at least correct enough for my purposes.