rjpierson commented in this post about how Jensen has come out with a head unit that supports the bluetooth handsfree profile. The Jensen MP8610BT is a MP3/WMA/CD receiver that has bluetooth so you can talk on your cell phone handsfree. I assume it will automatically mute the audio when you talk on the phone.
I was really interested in getting one of these for our Sentra. When I was looking for more information on it, I saw that the major electronics manufacturers are planning on adding bluetooth support to their head units. I assume that they will be announcing these at CES. The main thing that I want is a head unit that has built-in bluetooth and is satellite radio ready, so I think that I will wait for their announcements.
For our Odyssey, since the head unit is integrated with the navigation, I was looking at the Parrot CK3100. This would allow my wife and I to use our cell phones in the car without having to deal with wires. I saw that Fry's had these for about $150, but I didn't want them to install it.
So now, I just want to find a auto electronics installer that has experience installing these devices, and will make the install look as "stock" as possible. Unfortunately, the installer that installed the XM radio in the Odyssey has gone out of business. I am interested in finding a small installer around this area.