The most recent release of the Adobe AIR SDK is version 2.6. With this version of the SDK you can target the AIR 2.6 runtime on multiple platforms. However, one platform that you cannot yet target yet is the BlackBerry PlayBook. At launch the PlayBook, device and simulator, only support the AIR 2.5 runtime. This means that any application which targets anything higher then AIR 2.5 will not work on the PlayBook. There are a couple of things to consider when developing for PlayBook using the AIR 2.6 SDK.
The first and biggest issue is that the newer versions of the Flex 4.5 Hero Framework only support AIR 2.6. This means that you will only be able to create ActionScript only projects, which do not use any of the Flex Hero components. The public preview of Flash Builder 4.5, which is available on Adobe Labs, contains a very early version of the Flex Hero Framework and targets AIR 2.5, which is why this works today. However, when Flash Builder 4.5 ships and anyone using the pre-release version will not be able to create Flex Hero applications for the PlayBook until the runtime is updated.
When using Flash Builder and the AIR 2.6 SDK for developing your applications, Flash Builder will auto generate a application descriptor file, which targets the AIR 2.6 runtime. If you try to run this in the Simulator or on the PlayBook device the application will instantly crash without any real reason. There are 2 small items that you can do in order to workaround this issue. These steps are meant to be done with the BlackBerry Tablet OS AIR SDK 1.0.1
First, you need to make sure you compile your swf to Flash Player 10. This can easily be done with the following command if you are using the command line. -swf-version=10. If you are using Flash Builder you can go to Project > Properties > ActionScript Compiler and place it into the Additional Compiler Arguments field.
The second thing you need to do is force your application to target the AIR 2.5 runtime. Because you may be targeting AIR 2.6 for other platforms you do not want to change it directly in the -app.xml file. To get around this the PlayBook has an option to force the air version to a specific value when packaging your application. To set this you can use the following command on the command line -forceAirVersion 2.5. Or if you are using Flash Builder you can go to Project > Properties > ActionScript Build Packaging > BlackBerry Tablet OS > Advanced and place the command in the extra packaging options field.
With these 2 workarounds you should be able to now target AIR 2.6 for iOS and Android and 2.5 for the PlayBook. I hope that helps solve some of the confusion people are having