Dries Buytaert and Benjamin Schrauwen released a new Spam-service, called Mollom.
Mollom is a web service that helps you identify content quality and, more importantly, helps you stop comment and contact form spam. On the downloadpage from Mollom you can see there is already a Drupal-module and a Java-class. But no PHP class.
So here it is. My own open-source PHP library to communicate with the Mollom open API. You can dowload it from: http://mollom.crsolutions.be. Documentation can be found in the class itself or at http://mollom.crsolutions.be/docs.