I've upgrade this site to Leonardo 0.7.0 which I'm about to release.
It includes an enhancement to the comment module by Bryan Lawrence that provides for a maths-based captcha to help prevent comment spam. Basically you'll need to do a simple addition to post a comment.
Hopefully this will stop the literally thousands of automated spam comments I receive each month.
The original post had 5 comments I'm in the process of migrating over.
There may be broken links to media on this page. I'm still in the process of migrating them over.