On unit #2, repair #2
I received my first 27" iMac i7 quad core in mid January 2010, after nearly a 3 week wait from placing the order.
On initial inspection the unit seemed fine, but once the lights were lowered in the room, the yellow tinging was evident in the bottom right corner of the screen.
Apple was quick to order my replacement, which after nearly a month, arrived with an even worse tinge. This time evident in the entire right side of the screen.
We resolved to have the second unit repaired at a local Apple Store, while I held on to the original to continue my work.
After waiting another 2 weeks for the replacement screen to arrive, the Apple Store was able to make the repair in 2 days.
Sadly, this display is the worst one I've seen yet. Sadder still is the fact that it is supposedly a second gen screen for the 27" iMac. Apparently Apple has not quite figured out what they're doing wrong.
I just ordered my second replacement screen, and fully expect to wait some weeks more for a resolution. Unfortunately, my confidence in the quality of this product is very shaken.
Apple has been very helpful, but I wonder how many thousands of dollars they are losing trying to get this right.