It seems that
The two A2DP headsets we tested with the iPhone 4 were the
With the Nokia headphones, however, we had a few more issues. It took several attempts before we managed to successfully pair the BH-905 with the iPhone, and even then we couldn't get the music to play--the music played only through the internal speaker and the Bluetooth symbol was grayed out on the iPod music playback screen. However, after another round of disconnecting and connecting, we discovered that if we pressed play on the headphones, the iPhone would finally stream music. For comparison's sake, we also paired the Nokia BH-905 with an iPod Touch running iOS 4, which needed no such trickery to start playing music.
We would obviously need a larger sample size to really figure out for sure if there is an issue here, but we think this proves that the iPhone 4 is indeed compatible with A2DP stereo headsets. However, your setup may vary and it seems that some headsets may prove to be more troublesome than others.
We're curious to know if this has affected anyone else, and we would love to know if any new iPhone 4 owners have run into similar issues with A2DP connectivity. If so, please let us know in the poll, and also voice your experiences in the comments below. If you've had problems, definitely let us know what model headset you were using.