I'm sure it has. But it's a numbers game. I've found that Wikipedia entries generally reflect the consensus view of society at large. What your attitude about Wikipedia says to me is that either 1) your views do not reflect the consensus of society at large, or b) those who have self-selected themselves as diligent editors of pages on subjects you care about generally disagree with your opinions. In either case, the way to fix the problem is get more people who agree with you to diligently edit the relevant entries.
Discalaimer: I use Wikipedia for research on technical issues, not for research on political issues.
Good point. I've never seen bias, but I've never looked up anything that brushed against an ideological bone of contention.
For science and engineering, medicine, technology, factual(non spinworthy) history -- things like that -- it's the best site on the web, hands down. The articles are thorough and up-to-the-minute, and the links they provide go very often to original sources, you'll usually do much better to check Wikipedia before you try to extract something content rich from Google's search results.
It does my heart good to see so many people working together for free to produce something really, really good and useful for everyone to use. I use the search tool in Firefox to get results from Wikipedia, it's very handy!
Incidentally, I just checked the FR entry in Wikipedia, and it looked factual and accurate to me. Do some of us want it to be a flattering fiction before we call it "unbiased?"