From the Toys section for the new 3.0 iPhone software:
Amazon.com offers the Plantronics Voyager 855 Stereo Bluetooth Wireless Headset for $33.99 with free shipping. (You may have to click on "More Buying Choices" on the right).That’s the lowest total price we could find by $7. These sound-isolating Bluetooth headphones are designed to stream both music and voice from your new Bluetooth 2.0-enabled iPhone or iPod touch.
Note: Stereo BT won’t work with orig iPhone