I've tried my Sony Ericsson HBH-205 bluetooth dongle with my iPhone 3G. It pairs fine, volume, play/pause and mic work fine but the next track/previous track dont work.
Same here(not the mic) with car audio bluetooth and with another motorola handsfree BT. What a failure IMO. The good thing is that all the audio sounds in the BT(video, games...)
Okay so does the mic on the bluetooth headsets work or not? The only reason I would possibly see for updating to 3.0 is if you could use a headset as a mic and be able to use mic apps for the ipod. The answer to this has been contradicted a few times.