Bluetooth A2DP not working with Philips SHB6100 Headset iPhone 3G

Im using an iPhone 3G with the 3.0 OS, and trying to get music over my bluetooth headphones. The phone connects to the headset fine (theyre paired, the icon flashes when the headset connects, etc), and the headset is reported as fully A2DP compliant.
However, when I open the iPod app, the bluetooth icon does not show at the bottom like I expected from the various screenshots floating around... I simply get the old volume slider, and audio still comes only via the speakers or headphone jack.
I have tried all the basic solutions - re-pairing the devices, turning things on and off, powering off the phone, etc. Nothing seems to happen.
Is anyone else having the same problem?
Is it specific to this headphone (the Philips SHB6100)?
Does anyone have any advice on how I might get it to work?
Thanks in advance for the help!
Iphone 3g Other OS