I need a renderer/parser in Javascript or Java for MediaWiki syntax which supports mathematical symbols and formulas.
MediaWiki uses AMS-LateX for its formulas:
http://en.wikipedia.org/wiki/Help:Formula
There are plenty of renderers for mathematical LaTeX available in Java, eg. http://jmathtex.sourceforge.net/, and JavaScript has eg. http://www.math.union.edu/~dpvc/jsMath/ and http://www.mathjax.org/ as well.