My wife and I just got back from exchanging her phone, and out of two new phones they checked, they both had the same yellow hue... their display unit didn't, and neither did the associate's Fascinate who helped us. I wasn't going to make them open more phones up as this store has been really good to us.
The associate said he thinks that may just be the way they are manufacturing them. If that is the case, perhaps it is the software, and there is a setting buried somewhere that can be changed. I'm not sure, but I am curious to hear about everyones results on their exchanges.