From Mike Potter's blog:
Today I'm happy to announce that I've started a new project called the (unofficial) Adobe PHP SDK, which is intended to enable PHP developers to build solutions with Adobe RIA technologies quickly. The (unofficial) Adobe PHP SDK contains samples and libraries that show how to connect to a PHP backend system with either the Adobe Spry Framework (for Ajax applications) or Adobe Flex (for Flash based applications).
You can download the adobe_php_sdk.zip file immediately, extract it and explore the samples and demos immediately.
In true open source fashion, all the code in the project is currently available in various open source licenses, and the content for the HTML page is available under the Creative Commons license.
There is a project hosted at Google Code for the Adobe PHP SDK, and a mailing list at Google Groups as well."