I have an 05 x5 Nav BT and a Verizon Treo 650. After speaking with Verizon, Palmone, and all of their technical assistance people, they have determined that the 650 is not compatible with the BMW. The phone will allow you to make one call but then go into a reboot loop.

Interestingly enough my wife has a Motorola 710 and it works perfectly in her 05 x5.

Maybe someday!

Until then my 650 goes back tomorrow and I have to keep using my 600 (one great phone by the way)