Scott Andrew - lo-fi acoustic pop superhero!

Dave Winer’s entreaty to developers to develop decentralized directories with OPML got me thinking about a little-used feature of Movable Type: category pinging via TrackBack.

Most people use TrackBack to notify other webloggers about a response to a particular post. The software that receives the ping has the option to create a hyperlink back to the referring post at the visitor’s own weblog.

Category pinging allows a visitor to ping an entire category of weblog posts. For example, I have a category for JavaScript-related posts. The category itself has a TrackBack URL. So if you’ve written a post about a clever JavaScript trick, you can use TrackBack to ping my JavaScript category. Provided that I have MT set up to do so, I can automagically create a link back to your post.

It gets even more interesting: TrackBack allows you to create post categories that automatically ping other TrackBack-enabled weblogs each time a post is entered into that category. For example, if you have a category dedicated solely to JavaScript topics like I do, you can configure MT to ping my weblog each time you enter a JavaScript-related post.

There’s some real potential here for knowledge sharing that goes beyond the post-to-post, follow-the-discussion relationship. A MT template that consolidates all the incoming pings (and creating the appropriate outbound links) for a particular category would essentially generate a directory from distributed sources.

Imagine the type of directories that would be generated if even a handful of experts in any field — law, CHI, digital media, antique collecting, whatever — started pinging each other’s weblogs this way. My guess is this could start with invitation-only TrackBack-powered directories.