There is a google group for developers using OOCSS:
http://groups.google.com/group/object-oriented-css
and the code from the open source project:
http://wiki.github.com/stubbornella/oocss/
I asked on the group if anyone knows of an existing WP template.
This worked for me:
1. Open header.php
2. Remove:
<?php wp_head(); ?>
If you just remove the header-img.php file without removing the code that calls it, you’ll generate php errors and potentially slow your site. Also, as far as I can tell, the default image will still be called (the blue one).