I've always known that Wikipedia is pretty left-leaning. The technical articles are pretty good, without much bias that I can see, but an awful lot of the other categories are pretty biased.
Mr. Rawles over at the Survival Blog has just published an excellent article on his experiences, and has posted numerous links to other sources that have investigated this.
I highly suggest you go RTWT, and follow the links to read more.
One of the links is to Conservapedia, which I've now added to the "Link-O-Rama" sidebar here.
Thank you, Mr. Rawles, for your post, and the links!