ThomasHambach

Inspired by the script written by Blair Vanderhoof, this plugin allows you to input gist files directly into your WordPress posts using a jQuery callback.
Currently supports: * Showing a whole gist. * Showing single file in a gist. * Showing certain lines of a single file in a gist.

Gist Embed

This plugin allows you to input gist files directly into your Wordpress posts with a click of a button.

dflydev

This project is available for forking on GitHub:
<ul>
<li>https://github.com/dflydev/embed-github-gist</li>
</ul>
Embed <a href="http://github.com/" rel="nofollow ugc">GitHub</a> <a href="http://gist.github.com" rel="nofollow ugc">Gists</a> into 
WordPress. Provides a shortcode for posts and pages but also has the ability 
to embed by hand in the event that a Gist needs to be embedded somewhere in 
the page that does not pass through the shortcode filters.
Examples:
<pre><code>[gist id=546764]
[gist id=546764 file=file.txt]
[gist id=546764 file=file.txt bump=1]
[gist]http://gist.github.com/546764[/gist]
</code></pre>
Cache is implemented with the Transients API to minimize delay on loading 
content. Default TTL (time to live) is 86400 seconds or one day.
<h4>Upcoming features:</h4>
<ul>
<li>Option for setting default TTL</li>
<li>Option to bypass cache entirely</li>
<li>Implement admin interface to control options</li>
</ul>

Gist Embed vs Embed GitHub Gist