Jspresso -http://www.jspresso.org- is a free and opensource framework dedicated to building RIAs that offer a desktop-like user experience. Among many improvements, one of the major features of this release is the native support of Adobe Flex as a deployment option.
All Jspresso-based applications will instantly run on the Flash plugin without a single, hand-written, line of MXML or ActionScript in their code base. Nor is there any GUI code generation involved. Jspresso relies on a generic Flex client engine that dialogs with the Jspresso Java backend through Adobe BlazeDS using a generic set of GUI commands. This approach relieves the developer from the DTO pain you usually find in this type of applications while still leveraging the style and power of a Flex client-side and keeping the development server-centric.
Last but not least, Jspresso applications, bootstrapped by a Maven archetype, build entirely in Maven and can be directly imported in Eclipse with full WTP support. The server stack remains unchanged (servlet / Spring / Hibernate) and all the previous frontend technologies remain fully supported.