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.

Guilherme Baptista

Embed GitHub, Gist or Bitbucket files.
See: https://github.com/gbaptista/wp-git-embed

Gist Embed vs WP-Git-Embed