GitHub Gist WordPress Plugin allows you to embed GitHub Gist snippets with a [gist] tag, instead of copying and pasting HTML. For example, to embed the github_gist_wordpress_plugin_test.txt file from gist: 447298, fill in the id and file attributes in the [gist] tag:
[gist id=447298 file=github_gist_wordpress_plugin_test.txt]
or
copy the embedding JavaScript code from GitHub and directly paste it in the body of the [gist] tag:
[gist]<script src="http://gist.github.com/447298.js?file=github_gist_wordpress_plugin_test.txt"></script>[/gist].
The [gist] tag also expands the content of the embedded Gist and wraps it with “<noscript><code><pre>” so that search engine spiders, users with javascript disabled and users reading your blog through RSS will still see your code in a blog entry.