Read / Write Web reports on Adobe giving back to the community by offering Flex as an OpenSource development platform:

Adobe Systems announced last night that they will be open sourcing their Adobe Flex framework so developers can access their source code to enhance its ability to create Rich Internet applications. The Flex SDK and docs will be available through the Mozilla Public License. Adobe Flex, initially released in 2004 by Macromedia, and available since 2006 as a free SDK from Adobe, is a set of technologies to support the development of RIAs, web apps with the features and functionality that mimic traditional desktop applications.

By open sourcing the technology, Adobe is realizing the potential of embracing the developer community. By providing open tools they are helping to foster a developer environment that can result in the creation of cool features and functionality and further developer the framework to suit developer needs. Other open source projects from Adobe include the contribution of source code for ActionScript Virtual Machine to the Mozilla Foundation and the open source WebKit engine in the Apollo project.

With their latest open source release, developers are able to download and contribute to source code for the Flex compiler, components, and application framework. What is not included in the release is Flex Builder and Flex Data Services. Flash itself will also remain closed. Because some companies may not want to use the open source framework, Adobe still offers its commercial licenses with variable terms. I suspect that not many will opt for the paid license route, however. Adobe Systems has set up internal processes to ensure that security and stability remain core elements of Flex, knowing that any security breaches could be disastrous.