On the Ibuildings blog today there's a new post from Soila Patajoki about a white papers they've developed covering continuous integration and how it relates to PHP applications.
This new white paper discusses the policies and systems that together make up Continuous Integration. It explains how Continuous Integration can allow your teams to build projects faster and cheaper, and also covers several best of breed tools for PHP-based companies to use to implement such a system.
The PDF download is free, but you'll need to give up a little personal information to get to it. The white papers covers topics like source code control, regression testing and tools like PHPUnit, Phing and phpDocumentor.