At shdhvan on Friday, Liz Henry (who is most excellent and knowledgeable by the way!) and I started riffing on forums and communities and came up with the following pseudo-manifesto for social software:
Surprise, surprise, most wikis and most content management systems and blog systems like Socialtext, Drupal and Wordpress do most of the above things; most forums don't. Which is why forums make me uncomfortable; lots of forums have great content but they are impossible to follow, ugly and have really bad 1990s style URLs replete with question marks and ampersands which are not hackable.