Looks like there is some competition for your blog comments. Disqus and Intense Debate are both offering plug-in’s which really will change how your blog comments look and feel. User profiles, threaded comments, comment rating and even a forum for your comments are offered by both. I’ve not tried either as I would have two main worries.
1) Where are the comments held and could I move to another service with ease or just back to WordPress?
Ultimately one of these (there are other services too) will start to dominate and maybe then I’ll take a look. It would be great if some of the bigger sites like Digg or BBC supported one of these services so you could have a standardised commenting system to use on any site. Certainly Intense Debate seems to have the most features, including OpenID support but their name is really bad. One to keep an eye on.