I got the first defective IPhone 4 in North America... :(

Actually looking at the photo posted on Engadget:
http://www.engadget.com/2010/06/23/poll-is-your-iphone-4-retina-display-seeing-y ellow-spots/

And comparing it to the iFixit iPhone 4 disassembly:
http://s1.guide-images.ifixit.net/igi/WARyUnA2lknP3XOt.huge

There seems to be a circular hole in the inner screen shield right where the supposed yellow dot appears. That correlation is probably significant.

Perhaps a temperature issue? Heat from the A4 chip coming directly onto the screen without diffusion?

Would the yellow dot go away if the iPhone 4 was switched off (not just stand-by) to cool down?

I have the same problem as the OP. This picture is pretty terrible Picture of Iphone 4 screen taken with Iphone 3g. The picture does not look near as bad as it does in person. I noticed this problem the very second i turned on my Iphone 4

http://img.photobucket.com/albums/v243/adamdenterkin/Iphone4.jpg

I would also like to add, that i spoke with Apple, who sent me to ATT, that sent me back to apple again. Everyone was nice, but there was quite alot of confusion as to how to deal with these early issues. Because ATT will not have any phones to replace mine, Apple will be the ones to deal with the defective screen. They told me they cannot actually do the repair order until tomorrow when they phones are out, but i am first in line in the morning for repair orders.

She said most likely they will send a new phone out, and when it gets here i will be just send in the defective one. I do hope this is how they do this, so i can at least use the phone for the next few days.

I don't want to jinx myself, but after having the phone in the (air-conditioned) house for a few hours it looks like the discoloration is practically gone.

I downloaded one of those "flashlight" apps so I could illuminate the whole screen and I can still just barely see the discoloration, but it is definitely better now than it was when I first turned it on, and at this point I'd have a hard time convincing another person that there was anything wrong.

This is interesting. So perhaps it is temperature related?

Howdy all, Just got my 32gb iphone in black..looks great but NO the external speaker is dead!! no audio, no ring-tones. this is my 4th iphone. did the hard re-boot, did the restore, bluetooth is not on. Called support they told me it was dead on arrival.

I also have this defect....I believe there is quite a few phones like this from what I have been reading... I have two yellowish circles, one on the bottom right and bottom left. Very noticeable.

yup, I have the two yellow sploches in the left and right bottom corner too

I took a much better picture to show the problem on my phone. They are not yellow like some say they have. They are bright white spots.

http://img.photobucket.com/albums/v243/adamdenterkin/Untitled.png

I seem to have a completely dead speaker on my 32 GB as well. No audio whatsoever, a reboot and a restore didn't fix the issue.