I had my phone replaced yesterday for a pretty minor reason, but it was bugging me none the the less.
The seam where the chrome meets the black on my IPhone was uneven. It didn't affect the phone usage really, but it was very annoying to me when I picked up the phone, it was also starting to collect crud in the seam since it was uneven.
I made an appointment at the Genius Bar in the Louisville Apple store yesterday and went there after work. I spoke with Rick who was very helpful, he looked at my phone, acknowledged the issue and then said he'd just replace it.
I asked him about stock as I had heard they were out of 16gig which is what mine is. He said he'd just replace it with a service model, and informed me that since the 3G phone is so new, all the service models are brand new phones.
10 minutes later I walked out with a new activated phone.
Overall great experience, Apple's support is great. If you're in the Louisville store and have an Iphone/Ipod issue, I recommend you ask for Rick.