Ok, so I'm looking at Trackback auto-discovery. Assuming the ref is on the page, this is pretty simple. However, I'm looking at Sam Ruby's site, and no such refs exist. And yet his comments are filled with trackbacks. So I do a little investigation, and we discover that the trackback refs are in the RSS feed. So let's say I'm using a posting tool - I make a reference to this site. How do I auto-discover the trackback url for a post? Well, I have to download each RSS feed (there are a bunch there), parse it, look for trackback refs (to the specific post, no less), and then glom that information into my post. Is it just me, or does that seem like a huge, huge waste of resources?
When I'm adding a comment, getting this ref is easy - the aggregator can just look at the post information, see if there's a trackback url, and go to town. But on the posting side, it's just ugly. Put the frelling references on the html page being linked to, and make life easier for all of us. Gads.