I also had the same issue. I didn't read the forums about the headset - I had only used the headset only once or twice.
I walked into the Apple Store, they reproduced the issue, gave me a free loaner phone, and said mine would be repaired in 3 days. I'm still using the loaner till Monday.
I'll tell you this...I don't much care if there are one or two issues. If you get this kind of service, who cares. We'll all have problems from time to time, it's hardware, it fails.
However, I've never gotten this kind of service from AT&T. If you're phone is messed up, the service guys do everything they can do tell you that you dropped it or spilt coffee on it. I've never gotten an immediate loaner phone from AT&T or Cingular.
The real sigh of relief is that every time I synch, it's backed up so they asked politely, do you have a backup. Of course I did, but I never had this with a Blackberry - in fact - I had two Blackberries just in case. Thanks to Craigs List, they funded a 1/3 of my iPhone.
(P.S. Sorry to be a fan...)
Still the best phone I've ever had. So I'll let you know what happens to me.