categories vs tags

The way I see it, tags have only advantages over categories.
So once you use tags, what use is there still for categories?
Is there anything that you can do with categories, but you can't with
tags?

one thing i'm especially interested in: how useful are both tags and
categories for splitting up contents, even in rss feeds?

let me clarify.
suppose i have a blog about real life, technical stuff, and linux.

with categories, i could create a structure like:
/
/life
/tech
/tech/linux

with tags, i could have tag 'life', 'tech' and 'linux'

Suppose i would do a post about a linux conference, with
categories, that's both '/life' and '/tech/linux', but i can only pick
one; but if i use tags I can use both 'linux' and 'life'

But anyway, my real question is: is it possible to give people rss
feeds for specific parts of the site? for categories: a /life feed, and
a /tech feed, for tags a feed for the 'life' tag and a feed for
"any tag minus life"?
I assume the latter is not possible, which is exactly why there is
still a use for categories?

Furthermore, it would be cool (and useful) if anyone could
request a url like <baseurl>/rss20/!life/!bsd/music; which would feed
all entries except the ones who have tag 'life' or 'bsd', unless they
have the 'music' tag.

Another thing, it could be useful to incorporate category-functionality
into tags so that if i tag something as 'tech/linux' it will also show
up when i list everything with tag 'tech'


Dieter

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