Amongst his heavily medicated rantings, Mark Pilgrim points at something called Pingback. At a cursory glance, it seems to answer all my initial gripes about TrackBack. So, I think I'm going to take more than a cursory glance, and make an implementation in the next few days if I can't find one ready-made.

Some initial wishes for Pingback: How about making it two way? Ping a URL via its autodetected Pingback server, and also retrieve a list of pings for that URL from that server. Another idea, add a pub/sub method: I supply a URI to monitor and a URI of my own, and the remote Pingback server will ping me at my URI (via my Pingback server) when the monitored URI gets new pings at the remote URI. Require that the subscription be renewed weekly/daily. Make sense? One way to track conversations.