I have both previous iPhone models (2G & 3G) bought on the first day when they came out. Both units have gorgeous screens (the white is white not yellowish and the blacks are deep and dark not washed out). When the 3G came out I had to go thru about 5 phones to find one that had a good screen. All this "warmer" color is B.S. and do not let anyone sell you on it if you don't like it. For me is ugly, is not cool, is like a dentist that did a bad whitening job trying to tell you that yellow teeth are "easier on the eyes".
This past Saturday & Sunday I went to three Apple stores trying to determine if there is any correlation between the serial numbers because I went thru three new 32GB 3GS phones and all had the yellowish screens, however some units on the display had beautiful bright white screens (I tried to buy the smaller 16GB on display just for the good screen, but they would not sell it). At one place the store manager tried to convince me that there is nothing wrong with the phone and when I compared mine with the ones on the display he said that those were a special built. Then I asked him to show me his phone and his also had a bright white screen. I said that if he thinks they are all the same, I will buy him a brand new one, unopened from the store and trade it for his. He did not want to do it, of course. The real issue is that the yellowish screens have poorer contrast, color saturation and seem washed out when compared with the bright white ones like I have and also some on the store display (two stores had only 1 or 2 whither screens vs. 10+ phones that were yellowish). They were made on weeks 23, 24 and 25 and could find any correlation between the serial numbers and screen color (it may be but I could not see any pattern). The only option we have right now is to keep trying until you find one you like, go to the store, have them open it, if you don't like it don't take it and go back when they get more shipments.
At least three more people were in the store getting their phones exchanged because of the yellow screen.
Perhaps somebody at Apple will find a way to get it right as the number of returns and will grow and will start to become more costly than them doing nothing.
Do not accept the yellow teeth if you paid for white ones 🙂