I've found some interesting infos about porting a full
Linux to Android hardware:
http://wiki.openmoko.org/wiki/Openmoko_on_HTC-Dream

and some proprietary hardware drivers are userspace libraries,
which could be copied form the original firmware and be linked
by Linux applications:
http://www.telesphoreo.org/pipermail...ry/000495.html

so it seems doable!