While I was building this blog, I came across a jQuery plugin for converting Markdown and highlighting code in Disqus comments. By that time, unfortunately, the plugin was broken, likely due to changes in the Disqus API.
I have gone through the plugin to fix it for my needs. As part of that process, I removed code that I felt was trying to do too much. I think facilities for observing changes in the DOM library belong in a more general-purpose library like jQuery.
I have posted the code on Github for collaboration and maintenance.