I noticed that in Panther the Address Book dialog that comes up when you receive a call on a Bluetooth enabled cell phone no longer displays as the topmost window. That is, in Jaguar this dialog would display no matter what application you were working in. In Panther, the dialog displays but it is the only the topmost window within the Address Book windows ... so if you aren't currently working in Address Book you may never even see the window. Not a show stopper, but definitely an annoyance.
OAW