**Add file extension to Gedit syntax highlighting template**

You can add file extensions in the html syntax coloring scheme by editing html.lang in 
<code>
/usr/share/gtksourceview-2.0/language-specs/
</code>

as a super user. So say you want to add HTML syntax highlighting to cfm 
files, you'd change this
<code xml>
<property name="globs">*.html;*.htm</property>
</code>

(default html.lang) into this
<code xml>
<property name="globs">*.html;*.htm;*.cfm</property>
</code>