The update to Flash Builder and Flex that allows developers to create mobile apps for iOS, Android, and even Playbook, has been in beta for a while now. You may remember there was even a bit of a brouhaha over it. But all that is behind us now, and Adobe have officially released the updated application development environments.
What this allows developers to do is use existing code for Flash and Flex applications, traditionally delivered via the web, to create mobile applications. If you develop your Flash/Flex application in the proper way this can be a huge time saving when targeting multiple platforms.
For more information on how to upgrade and what exactly this means for Flash Builder and Flex, take a look at the Adobe Flash Platform Blog for the details, links, and videos.