[wp-hackers] Single Category Store across Sites on Multisite?

[Mike Schinkel]

This question got me thinking about if it is possible (practical?) to have a single category store across sites on multisite?  

http://wordpress.stackexchange.com/questions/6722/can-you-have-a-single-set-of-canonical-categories-shared-by-all-blogs

The more I think of it the more it seems like it just wouldn't be viable.  Anyone have alternate experience?

-Mike