The ))UniWakka(( wiki clone
has a very comprehesive math support.
They generate MathML, not pictures like wikipedia.
As far as I understood they use a php script that can convert ASCII representation of math to MathML so no latex or other external progs are needed.
Here is their math demo page
I'm currently trying to create a ))TikiWiki(( based student site at my university, math capabilities are highly wanted there.