I like trackback. It enables me to indicate that I am pointing or referring to something I’ve read and/or commented on without trying, and have readers of the original article see that debate. And reciprically I can tune into follow-ons from my posts.
Imagine if a news site like the Guardian, or the BBC, implemented trackback. The reader of the original article could then explore the responses to that article – both sides of the debate, different views, more information etc.
The difficulty would be working out how to filter out the “read this and it’s interesting” posts from the posts containing commentary so that the signal to noise ratio is improved.