First, I don't think I would be delighted by an automated puzzle on HN. Second, the idea that puzzle-solving-ability is somehow closely related to interesting/

First, I don't think I would be delighted by an automated puzzle on HN. Second, the idea that puzzle-solving-ability is somehow closely related to interesting/insightful writing is specious. People are smart in different ways, and as a programmer myself, the kind of smart that I want most is the kind I don't have, which is often not the problem-solving kind. All that having been said, I'm not against a captcha. I just don't think it'd be delightful and I don't believe that it'd somehow raise the quality of posts around here (beyond from removing some spam).