CAPTCHA'sI think motivating the need for CAPTCHA's and showing experimental data that indicates in only a minority of cases the human user will have to fill in the CAPTCHA form is a good thing. It might make people more accepting of the fact that if they encounter it, it's because it is really necessary, and not just some standard part of the submission procedure. Given this, I think such data may actually motivate site owners to start using Mollom rather than simply raising an extra barrier in the form of a CAPTCHA in every case. Good work!