I saw this thread yesterday and I was wondering about using symlinks or similiar to do this.

I.E. replacing /usr/bin/facebook-meego or /usr/bin/facebook-starter or /usr/bin/Facebook with a symlink that points to the fmobi binary.

As I see it this has a potential problems in the OS executing a command such as /usr/bin/Facebook some-command and fmobi not knowing that command. But the limit of my knowledge was coming up with this idea, I'd be willing to help experiment if someone will point me in the right direction if this is even possible.