writes "This was a surprise, for me at least:
From Adobe Labs: "Adobe is announcing plans to open source Flex under the Mozilla Public License (MPL). 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". ...
"The source code for the Flex SDK will be available under the Mozilla Public License (MPL). The MPL will allow full and free access to the source code, allowing developers to download, extend, and contribute to the source code for the Flex compiler and framework classes. The Flex SDK will also be available under a commercial Adobe license. Offering a choice of licenses serves the needs of enterprise Flex customers and partners.""