After several requests, I made the code available in plain text for the technical report Implementing a Rating-Based Item-to-Item Recommender System in PHP/SQL.
As an added bonus, Matt Gersting ported the code succesfully in Cold Fusion. I don’t know whether he will make it available or allow me to make it available, but he confirms the code works.
So, if you are a PHP programmer, you have no reason not to jump into collaborative filtering/recommender systems!!!
(But don’t just take the code, read the technical report as well!)