Disqus is a hosted comments solution, a popular one at that. What it does is that it replaces the comment functionality on your blog (or site for that matter) with a hosted one, which means that people can sign in with one username, and you get a lot of cool features without having to mess with plugins or code on your own.
The Mini-Profiles is pretty cool, but the killer feature is the Twitter sign in, available thanks to the new OAuth support (for you techies). Not only can you sign in with Twitter, you can also synch your commenting with your tweets, which is cool. Check out the Disqus blog post for more, or try it out yourself on any of these blogs.

Want an avatar? Get a gravatar! • You can link to this comment
Yup! Comments encourage people to write even more. They are like psychic wages that inspire you. On the other hand, they also offer constructive criticism by which you can improve.
Want an avatar? Get a gravatar! • You can link to this comment
It’s the threading of comments that makes DisQus a winner for me.
Want an avatar? Get a gravatar! • You can link to this comment
Using Disqus like a madman at our new site: http://www.localblips.com. Promoting the Twitter tie-in, too. Thanks for the post, Thord.
Want an avatar? Get a gravatar! • You can link to this comment
I have seen Disqus and i am using it currently, its really good to use and easy to comment.
Want an avatar? Get a gravatar! • You can link to this comment
mumbai is experiencing some really funny weather!!
Want an avatar? Get a gravatar! • You can link to this comment
Haven’t a clue how to use this site