Pingback seems to be picking up more support; Simon Fell has been busy implementing for Radio. Meanwhile, Aquarion has got Trackback working in Epistula, and Sarabian has enabled Trackback at From the Orient. Sam Ruby notes that “the primary advantage of TB over PB is that TB adds access to the excerpt”, although Simon Willison‘s implementation of Pingback retrieves an excerpt from the pinging page, so that’s not an insurmountable problem. Greg Reinacker notes in a comment that PB and TB seem to require “pretty much the same” amount of code on the server in his implementation, and TB requires more on the client, the latter point in agreement with Sam. Phil Ringnalda summarises the differences and how both have bled a little into one another in a comment.
All in all, we’re getting closer to the point where cross-linking all works neatly; the original purpose of Pingback was to enable a user to travel back up the ladder of links (it’s easy to drill down by following links, but you can’t go back upwards), and Trackback was (as Phil says) designed to make it easy to collect relevant conversation together (TB is a more social thing; PB more technical), but as a combination they seem to cover a lot and be getting wider support. Excellent.