Quoting Jan Steinman, from the post of Wed, 30 Mar:
While working with my wiki, I want to create different layouts for different peaces of my wiki. I could just install different mediawiki's, but that is a bit too much space consuming...
I installed *one* copy of MediaWiki 1.4, then wrote a script that duplicated the directory structure and hard-linked the files. Result is multiple wikis in nearly the same space. (Unix only -- I don't think you can do that in Windows.)
well, hardlinks, surprisingly enough, are possible in Woodnose, but M$ will not admit it openly, rather burry this fact deep in some MSDN article they hope nobody reads :-)
This might not be exactly what you're looking for, but may be a place to start.
sounds like he was looking for different thing, if I understood - different CSS for different pages in the SAME wiki...