Adobe has introduced their game developer tools for the Flash platform. (Now available on the creative cloud.)
Scout (formerly project Monacle) gives the developer a superior profiling tool during development and optimization of flash-based content.
The Adobe Gaming SDK includes libraries for Starling, Feathers, and Away3D. It leverages usage of your target device GPU.
The Flash C/C++ compiler (formerly Alchemy) takes your C/C++ code to target the Flash player. (Update: This has now been open-sourced as Flash Crossbridge on github: https://github.com/adobe-flash/crossbridge)