As far as I know, usually N900 had its USB connector torn off.
(That way smaller or larger part(s) of PCB traces are remain at connector side instead of the PCB, so it is also a question of luck.)
That means it is usually not as simple as soldering any connectors back to the board but also USB lines should be found somewhere on the PCB.
Basically it has GND, VCC, DATA- and DATA+ connections and if I remember well, it also used fifth connection to identify a proper charging cable.
So to tell something valuable, one have to see the phone, especially its PCB and only may say somethi