To me it just looks like the colour balance of the screen is set warmer. When I got my 16GB 1st gen I thought the same as it looked noticeably yellower than my 8GB one. However, after using it for a few days, It looked great and my old phone looked too blue.
The 16GB 3G one I've seen today appears to have exactly the same colour balance as my 16GB 1st gen and I can see why people who are used to the bluer screens would see it as yellow, but it's not a fault and it's not something to get stressed about and in a few days you'll get used to the warmer look of the new screens.
ATEOTD, they're not colour calibrated screens...