In the case of android "emulating" maybe is a too strong word. Don't know a lot about the architecture there, but maybe can be done in a similar way that was done the preenv "emulation", putting a compatibility layer to make dalvik and the android apps to run (in a somewhat native way, no virtual machine/cpu emulation) over it.

Regarding the architecture, if is the linux kernel with some extra (non conflicting with maemo) modules, and then an environment to run dalvik, maybe could be done with some help of the power kernel and something like easy debian. But is not the same saying that something could be teorically be possible to do than actually doing it.