Today I updated WordPress via subversion and there, just below the Post textarea on the Write > Post admin page, is a new tag inclusion area.
Granted I’m not on wp-hackers and have been definitely out of the loop lately tracking WordPress developments, but I think this is the opening volley for including tags in the WordPress core.
This February discussion on wp-hackers, Tagging, Categorizing, Labeling, Classifying: Taxonomics and Folksonomics in WordPress, seems to indicate that it was a possibility and this March 26, 2007 changeset shows the inclusion of a tagging backend for WordPress 2.2.
I think this is a good thing. Ultimate Tag Warrior is great. I like it, but I haven’t looked into all the bells and whistles it has to offer. I’m sure it can jump through hoops and make me a nice ham sandwich, but I don’t think I need it to make me that sandwich.
Having some basic UTW-like tagging options available immediately from a base WordPress install would be a very nice addition to the core. We’ll have to see how things progress.

I`m searching for a way to get the tag function out of the core easily again :) because i`m using the simple tagging plugin and its really better than the (csv) integration of wordpress tagging`s feature (till now).
I assume you’re referring to the Simple Tagging Plugin…is it actually conflicting with the tagging code being added to the core?
no, since 2 weeks or something about that its working fine in 2.2 or 2.3 csv´s :)
Since they aren’t bashing up against each other, I’d say you’re in the clear at the moment. I think you’re doing the right thing by keeping tabs on the WordPress tagging stuff as the code continues to mature.
I did have UTW going on this blog and I still may add it back. I’ve been mulling the this article, Not so ultimate WordPress 2.2 tags and trying to decide if I should just wait it out for UTW to play nice with WordPress again, or just hack away things to make it work again.