The IBM developerWorks website has a new tutorial (login required) showing how to use the Eclipse PDT functionality to debug scripts your PHP development.
The PHP Development Tools (PDT) plug-in, when installed with Eclipse Europa, gives you that ability to quickly write and debug PHP scripts and pages. PDT supports two debugging tools: XDebug and the Zend Debugger. Learn how to configure PDT for debugging PHP scripts and discover which perspectives you use when taking closer looks at your scripts.
You'll need to have a machine with PHP, Eclipse, Apache and the PHP Development Tools already installed to follow along (as well as a trial version of the Zend Studio Web Debugger). They also include the methods for setting up XDebug as the debugger.