I've used the 6280 with the ULF in my 2001 M3 and also 2005 X5: it works great. Nokia have coded all of the Bluetooth support including the (optional) OBEX. In the M3 I get phonebook transfer and SMS, the X5 though suffers from BMW Assist which means no SMS. However, I can't get SMS with anything and the X5.
As a rough cut Nokias which are so-called Series 40 tend to work very well with BMWs. I have used 6230, 6230i, 6280 and they have full support. Nokia Series 60s and 80s do not generally have Bluetooth OBEX, so the phonebook doesn't work. Check http://forum dot nokia dot com/devices/matrix_all_1.html
to find out which is which.

Good luck!

Thanks for the reply. Good to get first hand feedback.

Chris.