I just wanted to provide this information to you in case you were interested..
My car has handsfree built-in, so I can already make and receive calls via bluetooth, which is a beautiful thing that I highly recommend to all.
Unfortunately, the 2008 model didn't support A2DP and AVRCP, even though the 2009 does. STUPID manufacturers, at least our phones get updates at some point, my car never will..
Anyways, I have an Auxiliary input in my arm rest, right next to a 12-volt outlet, so.. naturally I picked up the Belkin Dual Auto Charger.
I chose this one because I wanted to be able to charge my phone, and power the BlackBerry BT Gateway.
The BT Gateway has a mini-usb port to power it, and a mini-stereo output port, which plugs directly into my car stereo's auxiliary input.
The end result? When I get in my car, the Droid reconnects to both devices.. Music plays via Pandora (hello 470MB usage in the last 2 weeks), and when a call comes in, the music stops, and the call goes through.
The BlackBerry unit is $80 at Best Buy, but only ~$30 on amazon