As much as I enjoyed creating the Rock/Paper/Scissors captcha [morerpscaptcha, rpscaptchasandwich, rpscaptcha] scheme for comments on this blog, the commenting system has otherwise been fairly primitive. I've been exploring ideas for enhancing the system and including some kind of global authentication like Google Connect, Facebook Connect, or Gravatars.
But it looks like a the guys at Disqus have most of this covered, so I'm going to give their system a shot. They support their own registration system as well as Facebook Connect, so if you have a Facebook account (with 150 million users, who doesn't these days?), you can post with your existing account.
Comments that were posted with the previous writeback system are visible below the Disqus comments.