Flash Component Kit for Flash CS3
Adding your great Flash content into Adobe Flex is now just a few steps away. You can easily export you Flash movieclips into Flex components with the Flash Component Kit for Flash CS3. The Flex Component Kit for Flash CS3 allows you to create interactive, animated content in Flash, and use it in Flex as a Flex component. This allows for designers and developers to add a creative touch to Flex.
Check out this video by Glenn Peuhle as he demonstrates how to create custom Flex components using Flash CS3.