n3ond4x writes "reCAPTCHA.net algorithms have been developed to solve the current CAPTCHA at an efficacy of 30%. The algorithms were disclosed at DEFCON 18 over the weekend and have since been made available online. Also available is a video demonstration of random reCAPTCHA.net CAPTCHAs being subjected to the algorithms."
There's probably an excellent Firefox plugin to render this page's color scheme more bearable. Note: the PowerPoint presentation linked opens fine in OpenOffice, and the video speaks for itself.