FYI -- This isn't a Mollom issue, but a configuration issue that might appear to be a Mollom issue.

Problem: The captcha wasn't appearing when the user was prompted to fill it in. Instead, all the user would see is "Word Verification * ()" followed by the submit box.

Solution: The issue was actually with our CSS. At one point in time we decided to hide links within the comment wrapper class, so '.comment-wrapper a' was set to display: none. As a result, the captcha never appeared.

Props to Sherlock Dries for deducing this... thanks buddy :-)