On the Bitflux Blog today (Christian Stocker) there's a posting about a simple, easy-to-implement naive PHP Bayesian filter.

Loic d'Anterroches by the way has implemented a PHP Naive Bayesian Filter that I could imagine would help me out the most with the trackback spam.

[...] By the way, the script by Loic did work right out of the box. ;) Looks cool. Simple API, and also did work for me out of the box. Maybe something for the BxCMS blog.

For those that aren't fluent in French or just want to check out an English version, see this link for all of the information. From the look of things, it's really a very simple script to add in to just about any kind of application that may come across your path. With the main functionality consisting of four functions (train, untrain, categorize, and updateProbabilites) and user-created categories, there's really not a limit to how one can use this script...

Download the actual MT script here: mt-bayesian-1.1.tar.gz (or our local copy). For the english version of the PHP filter, check out this page on phpGeek.com.

UPDATE: as a side note, there is also a Bayesian filter for Drupal that Jeremy Andrews has posted over on Drupal.org.