I've used the Nike +iTunes kit for a few years now while running. I first tried using the ear buds from Apple but they fall out of my ear while running. So I've been using some wired ear phones from Sony that attach over the ear. They work fine, but I can't stand the wire. So I'm in the market for a bluetooth headset that will stay in place while running. I started on Apple's website. There are not a lot to choose from, but the ones that are available are as follows (with Apple prices):
Plantronics BackBeat 906 (currently unavailable from Apple) but $76.94 from Amazon
Motorola S9-HD: $139.95 from Apple, but only $90.24 from Amazon
Plantronics BackBeat 903: $99.95 from Apple, but only $64.23 from Amazon.
Further Googling turned up the Sony DR-BT160AS. $77.49 on Amazon.
After thoroughly reviewing the reviews on Amazon I chose the Plantronics 906. I'll let you know how they work out.
February 26, 2010: Update Number One: Okay, so I got the Plantronics 906. I've run with it twice. It doesn't fit right, and it actually hurts to wear. It's difficult to adjust without 1) turning it off; 2) making a call; or 3) turning up the volume. I could live with this, but it constantly cuts out when I'm running. The freaking iphone is less than 3 feet from the unit! It's going back to Amazon, and I'll try something else. I definitely do not recommend the Plantronics 906.