Adobe flex provides a complete solution for building Rich Internet Applications. Its one of the main technology option for you to create compelling user experiences for today’s Java EE applications. In the Web 2.0 world of applications it has a major role to play. As we all know Sping is the most popular Java applcation framework. So the integration of both will be a good move to make a “Great web application”. I am only a beginner in this Web 2.0 world. During my search for this title I found this post by Mr. Christophe really helpful.
UPDATE- Feb 1st: This page will also helpful to you: Flex and Java