Trackback is dead! It made sense in a world without PubSub (or any other technology that can track links to anywhere on your site AFAIK Technorati and Feedster can't do this for free and/or for technical reasons. I understand Technorati's link search will be free but their site still says that you only get 3 watchlists for free.). Now all PubSub needs to do is offer an API (please give us an REST API; Jabber is fine but it's too heavyweight for most blogging systems and the need to run a Jabber server makes the barrier to entry too high!) so their link search can be built into blogging systems and it's game over for Trackback.
I remember back when Trackback was first introduced. I was like everyone else, jumping up and down at this new way of "threading the void". Well, we've just been hung dry on the threads and we've all come crashing down. AKMA writes today, "Trackback is broken", and I concur. It was broken right from the start, but we didn't know it because it seemed to work, or at least, work the way most people thought it should work.