If you are planning on using Math in mediawiki, and you have everything installed (Math, math, texvc, latex, dvipng) but you still get the error:
Failed to parse (PNG conversion failed; check for correct installation of latex, dvips, gs, and convert)
There is one last step that might need to be done. You will need to generate a latex.fmt file.You can do this with the command:
There is a good conversation about it over here.