Brier miscommunicated it.

cdent:

And this and Disqus both require that the person doing the comment establish an identity association with some service: it seems you gotta sign up. That’s adequate but not great.

For Disqus, an account is just a convenience, not a requirement. A person can comment through Disqus without an account.

But, I didn’t mean to proffer Disqus (or the others like it) as The Way, just as an answer to your specific question. The point I was trying to make, in fact, was that it’s not The Way.

The Way is for commenters to reply in our own web space, however we prefer, linking back to the subject. I’d rather we spent time building tools to help people locate and manage the distributed conversation than tools that, contrary to the nature of the web, try to centralize it.

Tumblr’s built-in reblogging mechanism is an interesting tool for tracking the conversation. It only does so amongst the Tumblr community, but it encourages the linking back to the subject that allows for broader tools.