Start driving using Navigation. It works remarkably good, speaking directions through the phone speaker, whether you have the Bluetooth headset turned on or not.
Then, God forbid, make or receive a phone call. I'm not even talking about EDGE, where you simply have the data channel disabled and lose the navigation altogether. I'm talking about bona fide 3G. What happens is...
you lose both the navigation and the phone call.The navigation, inexplicably, switches from the phone speaker to the Bluetooth, and just keeps speaking over the voice of the person you're talking to. Normal consequence is you can't make out anything of either.
Wonder if it is a bug or a feature, and whether it is specific to HTC G1, or common to all Android hardware.