A different approach to tagging?

A very different approach to tagging? Well, comments are closed over on that site, so I thought I'd voice my opinions here. That is after all, what I have this site for. In his post, Ryan is sharing his thoughts on the approach to tagging on Ask E. T., where Edward Tufte has the tagging system displays links to related posts, based on the tags applied to the active post.

The comments thread (on Ryans' post) may be full of critisim about the positioning of the links (on Edward Tuftes' site) - something which I also take issue with - but the idea seems pretty solid. Of course, if you're going to have related posts, it makes sense to draw them from the tagging system.

I'm currently using the related posts plugin for wordpress - I don't know how it works, but it does - and I don't have an issue with it, but I wonder what it would be like to do something similar to Edward Tuftes'. In theory, you'd just be adding a listing of all posts within a category, for each tag. It's certainly not a bad idea - if implimented correctly - so does that mean it is, in fact, a good idea? If we could get the listings into a condensed AJAX-ish dropdown, similar to the behaviour of the 'Share this' plugin, we might even be on to a winner...