On his blog today Piotr Walczyszyn has posted a tutorial on getting an Eclipse instance set up with the PHP development tools (PDT) and a Flash Builder plugin to get ready for developing Flex and PHP applications.
In this tutorial I will explain how to configure development environment to work with PHP and Flex projects in one tool. In order to do that I will use Eclipse PDT 2.1 (PHP Eclipse plugin), Flash Builder 4 Plug-in Beta 2 and latest Eclipse IDE for Java EE Developers package which is eclipse-jee-galileo-SR1-macosx-carbon (of course if you are on Windows you should get proper version instead) at the moment. Additionally I will use MAMP (Mac, Apache, MySQL, PHP stack), of course there are other possible solutions like WampServer for Windows, multiplatform XAMPP or Zend Server.
He links to all of the downloads for you (much appreciated) and walks you through the installation complete with screenshots and configuration settings you'll need to get things integrated.