Ben Metcalfe brings up something I hadn't thought of in relation to coComment, the weblog comment tracking service. coComment forks conversations, meaning it constructs a, possibly, alternative version of the comment stream. For example, on a site a comment might be moderated, edited, or even deleted by the site owner. But since comment "registration" with coComment is the purview of the comment author, coComment may still attribute the comment to the host site. Also, and I did pick up on this when I first heard about coComment, is that it only reflects the comments of those users registered with coComment and conscientious enough to use it regularly.
This arguably makes conversations on weblogs worse rather than better. I know I'm driving up VHS (blogs) vs Betamax (Usenet) Lane, but this is yet another example of reinventing Usenet, except worse. The only hope I really saw was in the comments to Metcalfe's posts, where someone proposed the use of a microformat standard to mark comments. Then a weblog search engine could intelligently aggregate the comments without circumventing the site owners prerogative.
And just as an aside, where are all those folks who were indignant about not letting blog authors opt out of Google's AutoLink, Microsoft's ActiveWords, or Third Voice? It's not apples to apples, since coComment doesn't purport to display content alongside the original site (yet it's an easy toolbar button away), but still you can argue that this eliminates some control of a blog's content by the author.
It all boils down to who owns the comment: the author or the hoster.
Of course, coComment is probably going on to wild success given my ability to predict the future.