E61i is a GSM/3G device. I doubt it will work in USA. I have a similar phone (E60, similar software) and I can try it on our X3, but as Eric said, I doubt it will work with the BMW. I've tried a N70 (older symbian software) and it failed miserably. It connects to the car, but always refuses to send the sound back to the car speakers (and no addressbook). On the other hand, I have the same issues with all my SonyEricsson devices (disclaimer: I work for Vodafone Group at Germany) - the only device that works 80% of the time is the K750, all others work only around 20%. Usually they work on the first call, but later they never send the sound back to the car.
I've kind of given up the bluetooth module from BMW.