Rob Saurini

It’s simple enough to embed a Gist, but the default embedded Gist behavior isn’t as easy to read as it could be. I’ve added line numbers and alternating line colors in order to give the gist maximum readability.
Use
<ul>
<li>You can use the shortcode [pretty_gist id=”gist_id“] to embed the pretty gist directly into a post</li>
<li>You have the option to change the default colors in Settings > Pretty Gists</li>
</ul>

Pretty Gists

Gives you the ability to add Github Gists to your site decorated with line numbes and alternating line color.

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>

Pretty Gists vs Embed GitHub Gist