Engadget notes that iPhone 1.1.1 seems to inadvertently allow you to stream music over bluetooth.

Oddly enough, this "function" has been unleashed by a Visual Voicemail bug that leaves Bluetooth audio on even after you've left the Voicemail interface.

There are still a few kinks... unfortunately, the audio also plays out of your internal speaker at the same time.

Update: This is reportedly not a new "feature", and was available on 1.0.2 as well.

Related Forum: iPhone