Flash Builder only recently released its much touted 4.5 release that brought support for creating mobile applications straight from Flash Builder. While the initial release of the Flex 4.5 SDK only supported Android, with version 4.5.1, the SDK now supports iOS, Android and BlackBerry Tablet OS with the same code base
This update includes the rendering performance improvements for the iOS that were to come with the iOS packager in the latest AIR 2.7 SDK brings, however the SDK itself still remains at 2.6.
Some of the biggest improvements to come with the AIR 2.7 SDK is undoubtedly the fact that it can now run Flash apps compiled for iOS as much as 4 times faster thanks to improvements in CPU-rendering. This improvement is part of the iOS packager, and thus are available via the Flex 4.5 SDK. However, the APIs developers will be able to use are limited to those available up till AIR 2.6.
This is been done so that the application developers can take advantage of the biggest improvements, despite the lack of synchronization between the AIR and Flash Builder releases.
It is however possible to overly the AIR 2.7 SDK over the current SDK and get the benifits of improved performance and new APIs.