MathJax isn’t currently supported out-of-the-box with Octopress. The main reason seems to be that the Markdown processor — rdiscount — doesn’t deal with the MathJax escaping very well. However, since Maruku supports it, I thought I’d try switching over.

I made the following two changes:

markdown: maruku
<script type="text/x-mathjax-config">
MathJax.Hub.Config({
      tex2jax: {inlineMath: [['$','$'], ['\\(','\\)']]}
      });
</script>
<script type="text/javascript" src="path-to-mathjax/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>

This allows for inline $\TeX$ expressions between dollar signs e.g. $\TeX$. MathJax display expressions (i.e. non-inline) are delimited by double dollar signs:

$$\forall x, y : \mathbb{Z}, x > 3 \land y < 2 \Rightarrow x^2 - 2y > 5$$

renders as:
∀x, y : ℤ, x > 3 ∧ y < 2 ⇒ x2 − 2y > 5

Right-click issue

There was also a problem with the theme. When right clicking a MathJax expression, the whole page goes blank! Zete has a great fix for this:

diff --git a/sass/base/_theme.scss b/sass/base/_theme.scss
index 9a50a8b..fc9dc37 100644
--- a/sass/base/_theme.scss
+++ b/sass/base/_theme.scss
@@ -75,7 +75,7 @@ html {
   background: $page-bg image-url('line-tile.png') top left;
 }
 body {
-  > div {
+  > div#main {
     background: $sidebar-bg $noise-bg;
     border-bottom: 1px solid $page-border-bottom;
     > div {

Futher reading

web