and here's some excellent (and dare I say) scholarly information from Wikipedia about the concept.
Note the authoritative references and external links to explore.
Update 04/07/12: I see that Wikipedia has put up some warnings about the lack of citations in the article.
Research Path Notes:
1. Found the video via @snbeach Sheryl NussbaumBeach, founder of PLPnetwork.com (Powerful Learning Practice, professional development for 21st Century educators).
2. Wikipedia: The Daring Librarian would be proud of me! Wikipedia is NOT Wicked!