I have seen a project that ports the Arduino framework to the ARM mcu family, but I can't remember the name of that project right now. They are also using gcc...
you can also have a look at this board which is at least pin-compatible with the Arduino:
ARMmite PRO
I hope that the Arduino project will support other mcu families in the future. But I guess we will have to wait since it is not even possible to include support for the Atmel ATtiny family in the official release.