I'm surprised this isn't high-lighted more in the update description. I updated my 3G iPhone to the 4.1 GM and I now have full bluetooth headphone controls: in addition to the previous controls of pause and volume, I can now track forward/back using the headphones.
This is a huge feature addition that will let me use my bluetooth headphones that much more without sacrifice.
This is a huge feature addition that will let me use my bluetooth headphones that much more without sacrifice.