One of the more popular code syntax highlighting tools for Moodle has been the rj_insertcode TinyMCE plugin written by Ryan Juckett. With this plugin you simply click the button on any editor and you are given the following options and text area to insert you code fragment.
The rendered code appears as follows. Its available to instructors and students on Scimersion. Attached is an updated version for Moodle 2.6.