i use to be one of symbian modder...i have make a few hacked filmware base on symbian v5 for 5800,5530,5230,5233....i have turn symbian filmware from basic to extreme version (fast & fully upgrade)...now i switch to maemo cause i don't have the fun hacking symbian anymore....
so as far as one of the symbian modder i know how the system are & for the idea to port it (dual boot) to n900 will not happening cause the system is to much different to be port...
n900 is a tablet phone so why you want use smartphone system where maemo system is far better than symbian???
you want to use some symbian applications such as 3G calling???
then you don't you just buy a symbian phone rather than waiting for someone port symbian system to n900....even if someone can port it do you thinks all features on symbian system can be fully working on n900??? if you do then perhaps you day dreaming cause even when modded C6 symbian system & port it to 5800 there is still many bug & features that i have to downgrade just to make it working on 5800....
imagine if porting from symbian to symbian is a major pain in the neck how can porting symbian to maemo will be????