"FWIW, as I recall, in that past the Arduino devs have said they don't intend to support an emulator in the IDE as actual hardware is considered an integral part of project."
That is an extreamly stupid statement for them to make if it is true. Anyone who has programmed micro's knows after the honeymoon you are searching for a way to develop faster without needlessly burning off write cycles. As the arduino provides for much larger programs, the cycle of "make a change, write it, test it, repeat" gets counter productive. (And a good reason people will switch from a stamp, i might add)