I have searched the forum on this, and while I am sure others have requested it, could not find anything on it.
It is time for the WordPress commenting system to integrate with the social web.
Here is how:
1. Allow people who leave comments to post their comment to Twitter, Facebook, Google+, etc.
2. Let people reply to comments by email.
I see Google is coming out with a system soon, but I am sure their system will ignore Facebook and Twitter.