I\'m starting a project using a Restful architecture implemented in Java (using the new JAX-RS standard)
We are planning to develop the GUI with a Flex application.
The short answer is yes, you can do RESTful with Flex. You just have to work around the limitations of the Flash player (better with latest versions) and the containing browser's HTTP stack limitations.
We've been doing RESTful client development in Flex for more than a year after solving the basic HTTP request header and lack of PUT and DELETE via the rails-esque ?_method= approach. Tacky perhaps, but it gets the job done.
I noted some of the headers pain in an old blog post at http://verveguy.blogspot.com/2008/07/truth-about-flex-httpservice.html