Went to AT&T two nights ago and got my iPhone 3GS 32GB. It didn't take long to notice that the screen is very yellow and washed out compared to my 3G. At first, I thought this was an intentional change, but then I walked over to the Apple store near my work and every 3GS in there (including 3 employees') looked blue-ish normal (like my 3G). Not one there looked yellow! My new phone has a 39 in the serial number. AT&T says they will exchange but cannot guarantee the new phone won't be of the same batch. The Apple store told me to take it back to AT&T. I walked back to work and called Apple Care for advice; they said the Apple store should have replaced it, made me and appointment and I walked back over. But then the Genius at the store told me they could only service the screen, OR replace my 20-hour-old phone with a refurbished model. They said they couldn't give me a new phone because it would "affect their retail numbers."
I work with Windows machines and VMWare ESX all day, and frequently nights and weekends. When I get home, I don't want those hassles. I payed the additional price for my iMac, my new Mac Mini (two weeks ago), and now this 3GS because of the hassle-free reputation of quality; in a nutshell, to avoid THIS.
I'm taking the 3GS back to AT&T tonight, paying their restocking fee, and going back to my 3GS which I like so much better. I really hope the next iPhone is more consistent.