As you should know, the new Stage3D feature of Flash Player 11 and AIR 3 provides powerful low level APIs to create high performance 3D graphics in Flash, the issue with this API is that it is of an extremely low level nature that makes it extremely difficult for average developers to pick it up and use it in their projects, and the expectation is that frameworks will be built on top of the Stage3D APIs that will be easy to use and are tailored for specific project needs.
Starling is the first framework built on top of Stage3D and is ready for use right now, this framework aims to help Flash developers create GPU powered 2D graphics that run at the high performance provided by Stage3D. The main highlight of this framework is that is uses convention display list architecture which means that you can pick it up and use it without having to spend a lot of time learning how things work.
Starling Framework projects will run on AIR 3 and Flash Player 11, unfortunately you will not be able to create high performance 2D games for mobile using Starling when AIR 3 comes out because the mobile version of AIR 3 does not yet support Stage3D, but Adobe announced that Stage3D will be introduced to mobile AIR in an upcoming update.
You can watch a video tutorial by Lee Brimelaw that showcases how easy it is to use this frame here, and you can also download a PDF handbook on the basics of Starling written by Thibault Imbert at this link. You can learn more about Starling Framework, look at the samples, and download the framework for your own use by visiting its official website.
Adobe has announced a few details about the upcoming versions of Flash Builder 4.6 and Flex 4.6 framework, both of which are expected to be released before the end of this year. In addition to incremental improvements in performance, Flash Builder 4.6 will introduce a number of badly needed components that are optimized for mobile projects such as SpinnerList, DateSpinner, ToggleSwitch, CallOutButton, and SplitViewNavigator, along with the introduction of the ability to use native text to support system wide text features such as text selection, spellcheck, and copy & paste. The update from Flash Builder 4.5 to Flash Builder 4.6 will be free of charge.
Adobe has announced that AIR 3 and Flash Player 11 will finally come out in early October, the main highlights of this new release is the formal introduction of Stage3D – a feature that will bring game console quality 3D performance to Flash Player 11 and AIR 3. Unfortunately, even though Adobe has been talking again and again about this feature and its use in mobile devices, the the release of this upcoming first version of AIR 3 will not support Stage3D in AIR 3 for iOS or Android and therefore you will only be able to use the new 3D features of Flash on the desktop. This means that we will have to wait for another update to the SDK to be able to create more powerful games for mobile.

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