On the Zend Developer Zone there's a new tutorial on how to use the combination of Doctrine and more PHP to connect with Flash Builder to create a simple classified ad system.
This article shows how to set up Doctrine and use it in PHP code. Then, it exposes PHP services to Adobe Flash Platform applications using Zend_Amf. You'll then call the Doctrine-enabled services from a Flex client. Finally, I'll show you how to switch your database from MySQL to SQLite with four lines of code. And I won't write a single SQL statement.
He shows how to set up a full Apache/MySQL/PHP installation with Doctrine, Flash Builder Alpha and the latest edition of the Zend Framework. He shows how to set up the models, connect Flash Builder to the app via the Zend_Amf component and how to build the frontend for the app inside Flash Builder.