Even if Sony just came out with a mini-USB headset that worked with the Sixaxis, I would be happy.
Not everything needs to be wireless, Sony. After all, this isn't like a phone where I put down the phone and drive while I talk on the headset. I have to have the controller in my hands, after all. It makes sense to tether the headset to the controller and remove any worries about battery life/charging the headset.
Not to mention that BT headsets are not made for the type of marathon sessions that gamers often use them for. They're made for infrequent, short-term use, like phone calls.
Or check out my new webcomic: http://selfcentent.com/