Adobe just announced that it will open source Flex under the MPL license.
I find this quite funny since when Flex was initially released you had to go through a stringent selection process before you were even granted a free developer license. At that time they judged that Bla-bla List didn't meet the requirements and my plans to create an alternative open-source version in Flex as a comparison couldn't go through.
When people have been asking me about Flex at conferences, I've been saying that to be successful it will have to be open-sourced. It seems they eventually realized that nowadays this is a requirement for any development platform. Kudos to Adobe for that.