The reliability of Wikipedia information has been an issue since its debut in 2001. 2001: Wikipedia goes online. Doing scholarly research will never be the same again.
Wikipedia takes the principle of the wiki and applies it to the encyclopedia, hence “Wikipedia.” Whether that is a felicitous marriage or not remains a subject of contention, a circular argument likely never to be completely resolved.
Wikipedia was the brainchild of Larry Sanger and Jimmy Wales. Wales gets the credit for the open-to-all encyclopedia concept while Sanger was, "sources" say, the advocate of using a wiki to accomplish this.
As of December 2007, there were more than 9 million Wikipedia entries in a variety of languages, more than 2 million of those in English.
Since Wikipedia entries are open to editing by anyone, and peer review is nonexistent, there is legitimate skepticism: What if the "editor" (or "Wikipedian," in the site's argot) is a liar? An idiot? Merely incompetent? What if two Wikipedians disagree over an entry and begin editing, and re-editing, each other? Well, if that happens and you don't cross-check the information, you're going to screw up your term paper.
But not all Wikipedians are mountebanks and fools, despite a few conspicuous exceptions. Wikipedia also has the advantage of being expedient, something not to be overlooked in this hyper age of "we wanted the information last week."
As readers have no doubt noticed, I use Wikipedia as a source for this feature on occasion. I have found it, in the main, to be reliable, but not reliable enough to depend on it as a sole source. (Of course, you shouldn't be relying on a single source in our beastly profession anyway.)
Still, it's not bad. Here's a litmus test: Read some entries in areas where you know you possess superior knowledge. You're a wombat expert? Check out the wombat posting and see if it squares with the hard truths as you know them to be. And, remember, you can edit the entry as you see fit.
There's a saying in the newspaper business: "If your mother says she loves you, check it out." If it applies to Mom, it applies to Wikipedia, too.
(Source: Wikipedia, among others)