With the WP-Syntax plugin that I installed this weekend you can write your comments with a clean syntax highlighting.
You only need to write the code between the
<pre lang=”LANGUAGE”> and </pre> tags where
`LANGUAGE` is a GeSHi supported language syntax. This means it recognizes several languages such as C, C++, bash and Perl that are the must used in this blog.
Check the first link for the different options that you can add to the <pre> tag.