Flex SDK 3.5, the latest official build, has been released for a few weeks on the Flex Open Source site and can now also be found on the main Adobe.com downloads page with the updated data visualization components. We are not releasing a new version of Flex Builder, but the 3.5 version will work in Flex Builder using the multi-sdk feature.
This release supports the security updated runtimes of Flash Player 10.0.42 and AIR 1.5.3. Additionally, it includes key bug fixes in the SDK, which can be viewed here (please login to the bug system to see this list).
The Flex 3 Language Reference have also been updated to 3.5.