Hi Mavrick
Not sure which BMW you have but it you go to this site
http://www.bmw.co.uk/bmwuk/bluetooth/0,,_,00.html?siteID=1312 and input your car details it will tell you which phones are compatible. If the iPhone is showing check which BMW software is required, you may need to update your car. Some 3 series are sompatible and some are not.
If it is just a case of updating your BMW software then take it to your local dealer and they can do this. It costs around £200.00 and the car will be in the garage for around 3 days depending on any problems.
As yet BMW have only tested the iPhone with software level 1.1.2 so as far as they are concerned if you have this software level and your car is showing on the website with the BMW software level,it should work.
I've feeling your car will need the latest BMW software in order to work, as you are still in warranty they my do this Free of Charge. Worth asking.
My dealer is very good if you get stuck, Dick Lovitt Bristol, 0117 905000.
Good Luck