I love tags! Unfortunately, most sites that implement tags only allow you to click on a single tag. I think this is why alot of people are bashing the move to tags. I think how the new tagging system on fm3 works is better than nested categories (btw: categories is just another term for tags now, so is GMail's labels) or nested tags.
I don't supposed fm3's developers could post a tutorial on how they created the tagging system along with the code used to navigate it could they?
In any event this site is MUCH improved with the new tagging.