Stephen Harris

This plugin allows you to write posts (of any post type) using the Markdown syntax. The plugin converts the Markdown into HTML prior to saving the post. When editing a post, the plugin converts it back into Markdown syntax.
The plugin also allows you to enable Markdown in comments and bbPress forums. In these instances the plugin adds a toolbar, and preview of the processed Markdown with <a href="http://code.google.com/p/google-code-prettify/" rel="nofollow ugc">Prettify</a> syntax highlighter applied (similiar to that used in the Stack Exchange websites such as <a href="http://wordpress.stackexchange.com/" rel="nofollow ugc">WordPress Stack Exchange</a>).
WP-Markdown stores the processed HTML, so deactivating the plugin will not affect your posts, comments or bbPress forums.

WP-Markdown

Version 1.5.1 of the plugin works almost perfectly.
I'm just waiting for the upcoming 1.6 update (which is in alpha on GitHub) to be pushed, so I can use GitHub Flavor-style codeblocks specifying the exact language.



Waiting for 1.6

Allows Markdown to be enabled in posts, comments and bbPress forums.

Jared Harbour

Josh Lyford

Prettify is a WordPress plugin that automatically embeds the required javascript for Google Code Prettify. It also includes a preview of what your code will look like and the ability to customize the look by installing <a href="https://wordpress.org/extend/plugins/themekit/" rel="ugc">ThemeKit For WordPress</a>. ThemeKit For WordPress is also on WordPress.org.
If you prefer you can run the plugin without ThemeKit and it will just use the default Prettify styles.
Features include:
<ul>
<li>ThemeKit ready.</li>
<li>Easy to use syntax and styling. </li>
<li>Same syntax highlighter as <a href="http://css-tricks.com" rel="nofollow ugc">css-tricks.com</a>.</li>
</ul>

Prettify For WordPress

Easily add Google Code Prettify to your WordPress site. Customize the coloring with easy with options powered by ThemeKit For WordPress.

WP-Markdown vs Prettify For WordPress