So, I have been looking around for ways to get Flex integration with Plone, because, imaginations and creativity that you can put with such a nice CMS on the backend and cool Flex in the front end is just endless.
My research so far uptodate includes, comments from techies that mention, using Repoze as a gateway interface between Plone and Flex using pyAMF.
Getting Repoze working with Zope:
Using pyAMF with Zope
Flex with Python
Integration of Python running on GoogleAppEngine with Flex
Some general Flex overview