I interviews Matt back in December 2008 for my media blog (which has been totally neglected due to family, work and my fishing blog which actually makes money). http://blog.metaprinter.com/2008/12/metafilter-founder-matt-...

In that interview he specifically states that he tried lots of different approaches for commenting / regulation / non regulation etc.

EDIT: The most community involvement I get is when i give something away. The The regulars and base community utilize the forums and self moderate, though i need to regularly post content for them to discuss.