In many of the more relaxed civilizations on the Outer Eastern Rim of the Galaxy, the Hitch Hiker's Guide has already supplanted the great Encyclopedia Galactica as the standard repository of all knowledge and wisdom, for though it has many omissions and contains much that is apocryphal, or at least wildly inaccurate, it scores over the older, more pedestrian work in two important respects.
First, it is slightly cheaper; and secondly it has the words "Don't Panic" inscribed in large friendly letters on its cover."
The Hitchhiker's Guide to the Galaxy, Douglas Adams
Let's be honest - even though large parts of it are fairly clearly written by academics, or at the very least interested amateurs with considerable knowledge of their chosen area of expertise (however weird or picayune it may be), the fact that Wikipedia is open source means that there's always some chance that the best-researched, most thoughtfully-written article can be completely buggered up (even if temporarily) by some asshat vandal with nothing better to do. That's the best-case scenario for topics which are sufficiently arcane or dull to avoid attracting sustained attention by the hoi polloi. For current topics or anything having to do with the standard hot-button issues of race, sex, politics, religion, drug use/abuse, or U.S. foreign policy (or lack thereof) it's a real struggle to even write about such subjects from a neutral perspective in the first place, to say nothing of keeping the article from being rewritten, "corrected" or just plain defaced every half hour.
If I were a university professor, I'd probably look a bit askance at any student paper citing Wikipedia as a primary source, although for a lot of articles the bibliographical information at the end provides a slew of references to books, journal articles, or more heavily moderated online works which are perfectly fine sources.
For all its failings, though, I could spend hours on the Wikipedia site, just jumping from article to article. I love the fact that in nearly every article, there are links to at least a dozen articles on issues which are either related to the original topic or explore side topics in greater detail. The main reason I love the Wikipedia, though, is for the stuff it covers that no standard reference work would even consider worthy of attention - the massive quantity of subcultural in-jokes, endemic memes, and pop-culture references that comprise the current cultural zeitgeist.
Any kind of information, once it's "frozen" in some form (paper, CD, DVD, etc.) becomes history. History is useful, certainly, but the threat of posterity tends to make one selective in what one writes. Wikipedia is a new kind of creature - the possibility of perpetual flux (even if in practice substantial chunks of it remain more-or-less stable after being uploaded), of being a snapshot of the sum of human knowledge (or at least what the people who write it are interested in) right now. And while accuracy and depth may suffer to some extent (at least in the short term), the breadth of information contributed is, as far as I'm concerned, a fair trade.
