The interview on C-span.

Some interesting points that I can very much relate to based on my experiences with http://www.wsuswiki.com and http://www.mswiki.com

Contributors to Wikipedia:

• 3000 authors that contribute more that 100 edits a month.
• There are set of even more active users that make 1000s of edits a month which bar far, contribute the majority of the content on the site.
• Wikipedia is ranked 40th on Alexa.

Who are the authors:

• Smart friendly people with targeted knowledge. He really emphasized the idea of being a social person and enjoying collaboration with other people to create new content.
• People who feel great for contributing to a great cause of documenting the human knowledge.