I think we should target to make the phone software completely open source. Identify what is closed source and investigate the feasibility to reverse-engineer or find a working (or need minimal tweaking) replacement. This achieves two things, making everything in the N900 open, thus giving developers free reign to mod/improve anything and everything they want and also opens up the possibilities to porting other OSes to the N900 platform which being completely open source makes it easier to port specific hardware.

Of course, it's easier said than done and I am sure many have thought of it, but I remember how the Atheroes drivers were binary only for linux distros and how the open source community slowly developed new completely open drivers using all publicly available documentation and working out the rest for themselves.

My 2 cents on this...