Thanks for the reply, MichaelH.
In my second post I wrongfully mentioned category names where I meant to refer to category slugs.
WP2.3/2.5 does seem to allow duplicate category names (so far) as long as it is a child category. It doesn't however allow duplicate slugs the way it allows for duplicate page slugs (if the page is a child page).
Apparently this is intended due to the new taxonomy stuff.
This 'new' behaviour doesn't really facilitate using WP as a cms, permalink-wise (I know, it is a blogging engine ;).
In my example above, the pre-WP-2.3 possible permalinks:
mysite.com/deutsch/projects/graphic/postname
and
mysite.com/english/projects/graphic/postname
would turn (for whatever categories are created last) into
mysite.com/english/projects-1/graphic-1/postname
Not very desirable, if one is nit-picky about ones' pretty permalinks. Any suggestions (besides using a different cms) are welcomed : )
Sidenote: Thanks for the howto-edit-the-slug-pointer, my test install doesn't use pretty permalinks yet so I missed that. Adding it to the admin menu when writing/editinging a post would easily be done with a plugin I guess