There was an interesting essay in the most recent CACM titled "Why You Can't Cite Wikpedia in My Class" (http://doi.acm.org/10.1145/1284621.1284635). The author, Neil L. Waters, is a professor
of history and the Kawashima Professor of Japanese Studies in the
Department of History at Middlebury College, Middlebury, VT. He recounts how several students submitted essays to him with incorrect information on several topics in Japanese history, and how he traced the incorrect information to several Wikipedia articles.