PHP and PHP Documentation plugins for KDevelop beta2 .deb packages for Kubuntu Jaunty 9.04 and Kubuntu Karmic 9.10 are available on my backports PPA. To install them:

Add my PPA to your system’s software sources

Install package kdevelop-php and kdevelop-phpdocs sudo apt-get install kdevelop-php kdevelop-phpdocs