Got the Motorolla v710 Bluetooth phone... works well with the Prius. I have not been able to sync the phonebook, though... I don't think I can transfer them :( The only way I can figured out how to add numbers to the system is to dial it out and then grab it from the outgoing calls list and add to speed dial. Even that doesn't allow you to add names, etc. Has anyone found a better way?

Also, the Prius doesn't seem to handle call waiting...

I've done some testing of various Bluetooth headsets for work... and of all of them, only one claimed to be able to handle call waiting. I couldn't get it to work.

I don't think it's very well-supported in the current version of the Bluetooth standard, especially using the headset or handsfree profile. I think handsfree might add some rudimentary support for call-waiting, but I've yet to see a good implementation of it, including headsets from Bluespoon, Bluetake, Logitech, Sony Ericsson, SouthWing, and a few others.

And since the Prius is just a really, really expensive headset, as far as your phone is concerned, I don't think there's much that can be done. Not sure if BT 1.2 does a better job of it, much less if the Bluetooth stack in the car can be updated in the future to 1.2, should that be the case.