PHPCI is a free and open source (BSD License) continuous integration tool specifically designed for PHP. We've built it with simplicity in mind, so whilst it doesn't do everything Jenkins can do, it is a breeze to set up and use.
We've got documentation on our website on installing PHPCI and adding support for PHPCI to your projects.
Contributions from others would be very much appreciated! Please read our guide to contributing for more information on how to get involved.
Your best place to go is the mailing list. If you're already a member of the mailing list, you can simply email php-ci@googlegroups.com.