This includes not only the source to the ActionScript components from the Flex SDK, which have been available in source code form with the SDK since Flex 2 was released, but also includes the Java source code for the ActionScript and MXML compilers, the ActionScript debugger and the core ActionScript libraries from the SDK. The Flex SDK includes all of the components needed to create Flex applications that run in any browser - on Mac OS X, Windows, and Linux and on now on the desktop using "Apollo".What does this mean to the average developer though? Well, it means we can get more involved in feature requests and discussing these with project committers as well as following submitted bugs through an open bug tracking system. Adobe will keep the builder separate of course as this is surely there key revenue for the project. Now time to sit back and dream of a time where maybe.... just maybe CFMX is free so the two can be combined into a powerful open source RAD environment to combat all languages.Press release
Adobe Labs Wiki entry
Flex open source FAQ
David Wadhwani, VP of Flex Engineering and Ely Greenfield, Flex Architect discuss the Flex Open source announcement with Robert Scoble of PodTech.