Program E is an AIML chatterbot written in PHP and using MySQL. It's composed by a converter which loads the AIML files into the database, a core rule engine that adheres to the AIML 1.0.x specification and several chat interfaces: HTML, Flash and XML-R
This is now "abandonware" form what I understand. There are a considerable number of bugs in the source. I recommend Program-O if you are looking for a PHP/MySQL AIML interpreter. If has a nice admin interface, has a nice AIML upload util (not a complete rebuild for one change), and an active support community for help. I was able to modify the source to customize to my needs, but when I hit a wall, the forums were very helpful.