It goes without saying that Wikipedia is old news now, and so are the various controversies surrounding its use as a source for scholarly work. However, I still think of the following as something of a coup...
I was reading my Nur435 textbook the other day--Keltner's Psychiatric Nursing, 5th edition--and noticed that it references Wikipedia at one point. If you have the book, it's pages 397 and 410. Keltner et al reference Wikipedia's "List of people affected by bipolar disorder." The citation on page 410 says it was accessed October 6, 2005. So, the author(s) would have been looking at the October 3, 2005, revision. (I don't know why I find it cool that I can go and look at this revision, but I do.)
Here, we just had Open Access Day, and now I find a hole in the wall of college textbooks, which are inveterate enemies of open access as far as I can tell. "Once more unto the breach, dear friends..."