[wp-hackers] Using Taxonomy for Users, Comments, Post Meta, etc?

[Mike Schinkel]

Hi all,

I'm having a discussion over WordPress Answers in the comments for this question[1] about the use of the taxonomy system for classifying items other than posts such as users, comments, postmeta, etc. I had been thinking it was a foregone conclusion that the taxonomy system was designed to be used with more than just posts but the fact that someone is making some good points to question that logic is making me question it too.

OTOH one of his arguments I still don't agree with is "If there are no functions to support the use of taxonomy for items other than posts then it's better to create new tables."

Can anyone speak to if 1.) the taxonomy system was actually designed with more than posts in mind,  2.) if anyone is using the taxonomy system successfully to classify items other than posts, and 3.) if anyone can comment on if adding new tables vs. reusing the existing taxonomy tables is more appropriate and why? 

Thanks in advance.

-Mike
[1] http://wordpress.stackexchange.com/questions/5974/creating-a-custom-admin-panel