Purely as information for anyone else out there, I can confirm Nokia's bluetooth headphones, BH-604, work with the N85.
Previously, I had used some Sony Ericsson bluetooth headphones with my N95 and these had demonstrated a "stuttering" or intermittent cessation of music during playback rather like quickly pressing pause and then pause again. I put this down to either the N95 or the headset being unable to process bluetooth info fast enough and thus becoming overloaded.
My new BH-604 headphones work fine with the N85 without interruption. However, on first connection sometimes the maximum volume can be quite low and it requires a disconnect and reconnect to "repair" the situation.
Hope that helps someone. If you want any more info let me know.
F