I went to my BMW dealer at lunch, and he told me that X5's from the factory (with Assist standard) don't come with a ULF, but rather a TCU. He also said he had paired a Treo with a 6-series last week. He tried to pair mine for about 20 minutes, and we kept getting the Reboot every time the "PHONEBOOK LOADING" message came up.

Here is the info off my Bluetooth card:

84.11 6946993-02
232925 23
USA 28.09.2004

BMW EVEREST IBUS US
SW:27 HW:35
BT:00E00C55E7F6
PK: 9383
ESN: 146-02440816
Bar code ||||
UAI0022408