Vikram Vaswani passed on a link to a recording of a webcast the folks over at Liip did about using the PHPCR (content repository for PHP) along with the Magnolia CMS.
PHPCR enables developers to use Magnolia CMS within a PHP application. Common scenarios include editing Magnolia CMS pages and creating or updating CMS page properties through a PHP front-end. With PHPCR and the PHP Jackalope implementation, PHP developers can interface with Jackrabbit, the JCR implementation in Magnolia CMS and can connect their Web applications with Magnolia CMS without any special Java training or knowledge.
You'll need to register to view the webinar, but it's an interesting look at integrating this (PHPCR) with a major system to house its content.