I am no PHP expert and to not intend to be one, but while I was searching how to integrate Flex with different backends, i came across some tutorials that i believe would help others:

• http://devzone.zend.com/article/11-Integrating-Adobe-Flex-and-PHP
• http://www.adobe.com/products/flex/features/video/mihai_corlan/
• http://www.adobe.com/devnet/flex/articles/php_getstarted.html
• http://devzone.zend.com/node/view/id/2019