While pursuing the internet (a favorite past time of mine) I found these videos. Even today, many people do not know 1) what a wiki is, and 2) how it could benefit them or their organization.
Here are some great videos that have teachers explain how their using PBWiki, but the ideas are applicable to any wiki software you’re using (we’re starting to use SharePoint 2007 at my work)
What is a wiki?
How does collaboration work?