There seems to already be some movement in this area: http://www.hjackson.org/blog/archives/2004/11/moveable_type_s.html
There was a similar effort for WP:
http://wordpress.org/support/10/12268
It was too difficult for most people to set up so it didn't get far.
A Big List of other things people have been doing:
http://codex.wordpress.org/Combat_Comment_Spam
-- Matt Mullenweg http://photomatt.net | http://wordpress.org http://pingomatic.com | http://cnet.com
