The standalone TrackBack tool serves two purposes: 1) it allows non-Movable Type users to use TrackBack with the tool of their choice, provided they meet the installation requirements; 2) it serves as a reference point to aid developers in implementing TrackBack in their own systems. This tool is a single CGI script that accepts TrackBack pings through HTTP requests, stores the pings locally in the filesystem, and can return a list of pings either in RSS or in a browser-viewable format. It can also be used to send pings to other sites.
It is released under the Artistic License.
TrackBack uses a REST model for its pings in order to ensure that each TrackBack item has a unique URL. Although Trackback is developed for blogs, I think it can be used much more widely. But not least, it can bring blogs and other systems closer together. I wonder which non-blog kind of application first picks up on backtracking?