One of the least-used features of Trackback, at least in the Movable Type implementation (has anyone else actually implemented it?), is the RSS feed of pings to an entry. Take an MT Trackback URL, like http://philringnalda.com/mt/mt-tb.cgi/335, and append ?__mode=rss and you get an RSS feed, with the channel/link pointing to the HTML page for the post, and item/links pointing to posts that sent pings.
I don’t remember much coming from it, other than Ben Hammersley’s More Like This From Others LazyWeb request, which seems to have mostly gone down the 404 toilet, but now as Ann Elisabeth notes, it’s become useful to at least one Trackback spammer.
Although my first thought was that it was a way to gather more spam targets, on the assumption that any URL which sent a ping was likely to also accept them, the more I think about it the more likely it seems that it’s just a way to find out what post the spammer needs to look at to see whether his spam worked. A good query for mt-tb.cgi will get you tens of thousands of targets, but since some people don’t even run MT off the same domain where they publish, it’s hard to accurately tell whether your spam was published, without knowing where to check back. Start with __mode=rss, and you not only know where it will be, you’ve actually got an easy way to check on whether or not it was blocked, and whether or not it was deleted later on.
Filed under: “no one can have nice things!”