Ha! I am all about the tag love. I could never get myself to use MT's categories for my blog, they just never felt right, but I think I'm going to give Cal's MT3 tag plugin a spin.

You seem to be up on this stuff, so I'm sure you've seen this M2M article on "folksonomy."

"Lack of precision is a problem, though a function of user behavior, not the tags themselves. del.icio.us allows both heirarchical tags, of the weapon/lance form, as well as compounds, as with SocialSoftware. So the issue isn’t one of software but of user behavior. As David pointed out, users are becoming savvier about 2+ word searches, and I expect folksonomies to begin using tags as container categories or compounds with increasing frequency."

Tags are like Venn diagrams. If you see where enough of the circles intersect, that little sliver in the middle is very precisely focused indeed...