Add in to the mix that the official reason Fremantle doesn't work in the N810 is because of the missing GPU. There's only ONE component in Fremantle using the GPU: the window manager. (The other components can't run because Fremantle is built for ARMv7, but that should be trivial to fix).

Now, the official reason for Harmattan not being available in the N900 is multitouch. Guess how many components and applications are using it? I'd be surprised if not ALL of them have some multitouch gesture.

If any, releasing, maintaining, documenting, and handling the UI differences for an official port of Harmattan for the N900 will be even more difficult for Nokia than releasing an official port of Fremantle for the N810.