Continuous integration for PHP projects oftentimes exist of merely running your latest test cases against PHPUnit and on success uploading your new file versions to your staging (or even production) server. Although Jenkins is able to handle all those tasks (easily) the way along numerous configuration steps can be quite painful.
With PHPCI a new potential big player is rising that was specifically designed for PHP based projects. Instead of manually setting up PHPUnit and PHPMD for instance all required testing and deployment tools are already built-in as first class citizens.
For more information you might want to read Dan Cryer’s interview in the latest Web and PHP Magazine issue and visit the project’s homepage at http://www.phptesting.org/.