i am also looking for this.
Hopefully, Flash player supports the format natively in the future like as easy as loading a jpg
But meanwhile i am sure it will be relativly simple to implement a renderer/parser for FXG with AS3 (willing to start that soon)
It will be a god send for CMS applications for Flash websites. (Having FXG editor and renderer)
I am %100 sure it will be possible to do this since FXG format is based on Flash player rendering capabilities
Ali Tan Ucer