If two "liberals" tell you that Wikipedia isn't biased towards the "liberal" side of things, doesn't that prove that it is biased, especially when the two "liberals" aren't exactly known for thinking things through?
OK, it's not proof, but it is a strong indicator, as Kevin Drum  approvingly directs our attention to the post from Eve Fairbanks  of the New Republic (also home to Jim Kirchik and Jason Zengerle). She discusses a subscriber-only National Review article (link) called "Liberal Web" which discusses liberal bias at WP, and says:
while I hadn't perceived anti-conservative bias on Wikipedia's political pages, I wanted to see if [John J. Miller] had picked up on something I didn't.
She then uses the fact that Miller only came up with two points to buttress her claim that there's no such bias. Obviously, she's engaging in a logical fallacy: just because Miller doesn't present more examples doesn't mean that there are no more examples and doesn't mean that better examples can't be found. And, in fact, many more can be found as I know from editing various WP pages from about 2004 to about 2007 when I basically gave up due to things such as perfectly reasonable, fact-based edits being constantly rolled back . In fact, I even created a site with a few examples at wikipediabias.com; note that there are many more that need to be added. Not all of the bias is of the "liberal" variety, such as that to be found at the Snopes entry.
And, it's perfectly understandable why there would be such bias due to the demographics of the web, which skews not just "liberal" and libertarian but also younger than the general population. Younger folks have more time to engage in editing wars, and those on the left side of things tend to be more activist than those on the right.
Wikipedia deletes, locks North American Union article
Google to just let Wikipedia control search results from now on
Liberals: Wikipedia not biased, Conservapedia a joke
AVWatch: will facts stick in Villaraigosa's Wikipedia entry?
How not to criticize Wikipedia
AVWatch: let's see how long facts stay in Villaraigosa's Wikipedia entry
Bloggers: stop linking to Wikipedia
"Wikipedia Celebrates 750 Years Of American Independence"
Wikipedia's continual low credibility
 washingtonmonthly. com/archives/individual/2008_04/013529.php
 I made a recent edit to the Bill Richardson entry, which was rolled back. I'm not going to get into a fight over it, but others might consider doing so: en.wikipedia.org/wiki/Talk:Bill_Richardson#controversies
Miscellania · Tue, 04/15/2008 - 14:37 · Importance: 1