But there is a fundamental thing that developers should remember: Interacting with flash application is a local activity without round trip times. So if you are forced to introduce round trip just because you want the app to be RESTful, I think it is not a good approach. Instead the URL in the browser should dynamically change with your interaction with the application.
Let me give example. Say you selected an user from the list, and want to send the URL by email to another friend. So selecting that user might trigger a URL-click, and some interaction between user and flash should ensure that URL will change in a browser, without actually going to the backend server. In other words, it is not a real URL click, but only a simulation.