Adobe has contributed its virtual machine to Mozilla's Tamarin project.
Under the arrangement, Adobe will contribute source code from its ActionScript Virtual Machine, which uses the scripting language engine in FlashPlayer 9.
From there, Adobe's code will reside in Mozilla's source code repository. Adobe will also contribute a team of developers to the open source project. In the overview of the Tamarin Project, Mozilla said the following:
The roadmap for the Tamarin project still needs to be cooked up, but it sounds like this effort is worth monitoring going forward. Here is the FAQ.
Ted Patrick, Flex evangelist at Adobe, has more background, but the goal for Adobe seems to be this: Open source its virtual machine code and become the defacto standard.