This edit improves compatibility with Markdown processors that output XHTML.

Jekyll and Octopress Liquid tag for MathJax.rb

module Jekyll
  class MathJaxBlockTag < Liquid::Tag
    def render(context)
      "<script type=\"math/tex; mode=display\">\n%<![CDATA["
    end
  end
  class MathJaxInlineTag < Liquid::Tag
    def render(context)
      "<script type=\"math/tex\">\n%<![CDATA["
    end
  end
  class MathJaxEndTag < Liquid::Tag
    def render(context)
      "%]]>\n</script>"
    end
  end
end

Liquid::Template.register_tag('math', Jekyll::MathJaxBlockTag)
Liquid::Template.register_tag('m', Jekyll::MathJaxInlineTag)
Liquid::Template.register_tag('endmath', Jekyll::MathJaxEndTag)
Liquid::Template.register_tag('em', Jekyll::MathJaxEndTag)

Solution from this email.