Correct me if I'm wrong, but by it's description, this plugin tries to do the exact job that custom taxonomies are meant to do (since WP 2.9, at least).
Disclosure: I have a similar plugin: Custom Field Taxonomies, but it has features that you don't get by using regular taxonomies (yet).
http://wordpress.org/extend/plugins/serial-posts/
Hi Scribu,
Yes, custom taxonomies can do this too of course, though they are not so easy to set-up for non-coders. Once custom taxonomies are easier to manage (ie set up) via the Dashboard, there probably will be little demand for a plugin like Serial Posts. In the meantime, it works, is simple to use and has its supporters. :-)