You can buy an app called: Blue Tint Cleaner for iPhone 4 in AppStore. It can somehow help removes the blue tint from the picture taken by iphone 4. Hope that help you from wasting your time travelling to MC and they will tell you stupid answers and wait for ages to get a replacement. About the yellowish screen... Don't worry, the longer you use your phone, it'll automatically fix by itself. Cheers!

98% of the iP4 will have that blue tint issue.
The yellowish display is common, and it'll auto fix by itself after 2-3 weeks of usages with max brightness.
It's caused by the residues not fully dried when the factory glue the layered glass.
Google it and you'll find the cause.

But if you find that there's white spot on the display or yellow/orange patches. Then you need to request for a replacement on the spot.
Enjoy!

I've 5 iP4 16GB and 32GB. All of it have the same issue. With very obvious and less obvious looking (still noticeable).
Go search macrumours forum and apple support forum. You will see most of them have it. The one who says don't have it is either they are not into photography or bull for self comforting. Do take a picture and crank up the saturation in any photo editing software. You'll see it instantly. Hope that is clear enough for you. You don't have to read from else where, but to test it personally to assure it's accurate. Unless you have a smarter way to proof that my facts is wrong. I'm not here to assume. But already knew ppl like your kind will shoot and ask the usual smart question like this all the time. Go ahead and try it. Peace

This post has been edited by S4a: Nov 12 2010, 05:32 PM