[styrmis]

Having a different URL for each update would allow them to track readers' entry points into the article at a finer-grained level than if there was just one URL.

Not sure about plugins for Wordpress but I wouldn't be surprised if someone's already started working on one.

Regarding the multiple URLs I wonder if it is more just so that they can be posting what look like new stories that ultimately just lead back to these long form story series.

[keithpeter]

The reference number seems to act as a permalink, so

http://www.fastcolabs.com/3009577/

leads to the original article, and I assume will continue to link to the article as they add content.

I wonder how the adding of new content rather than the reorganisation and re-editing of the article will work from the point of view of prose style?

[mtgx]

But isn't that the same as the automatic redirect you have in Wordpress when you change the URL of the post anyway? I'm trying to understand if there's any advantage to having this number stub over how WP redirects the URL's, but I don't think there is one. You're still going to get redirected links either way.