Just picked up an Iphone4 and I'm in buy accessory mode. I'd like to have something with great quality, solid battery life, and easy to recharge. I've haven't done headset in a couple of years when it used to suck.
I like my Motorola S9-HDs also. You can answer a call while listening to music so you don't need to take them off to answer the phone. But one drawback is that you can't use the controls on the headset besides the play/pause or answer/end buttons.
I bought a BlueAnt Q1 on Ebay for $43.00. I've always had good luck with BlueAnt earpieces - as far as noise cancellation and calls - but, this one seems more comfortable. Here is a good comparison between the Q1 and Jawbone Prime. Both seem like very good devices.