I've published a sample application that shows how a Flex client can use a Python service hosted in Google App Engine to create, read, update and delete objects. The Flex application is built with PureMVC.
I hope it can help people learning these tools and techniques. Also, feedback on how to do things better is most welcome.
The source code is hosted on github so anyone can easily fork it. I also authorize it to be included in the PureMVC samples area if it is deemed good enough for this.
More information here:http://fernandoacorreia.wordpress.com/2008/08/23/example-of-ria-in-the-cloud/