I'm sorry to hear that, i also got the 9c66 but i'd say it has no yellowing, even though when you use the 2 images for a test, the bottom square is not as bright as the top one (even looking from different angles), but i was concern that maybe that still was a defect, so i compared my screen to a friend's one (which was a 9c67) using the images, and the result was the same, actually his was probably slightly worse from this point of view (but i must say that the color gradient on his LG is better than mine).
I also run the test on a friend's mac which is a powerbook G4 and again the 2 white squares were not identically bright.
The only mac that i tested so far where the 2 squares are 100% identical is a iMac that i use at work, so i wonder if that is a common problem of laptop lcd...
So i am sure that out there someone has really a yellow bottom, but i am also wondering if anyone is actually confusing the yellow bottom with this other problem...getting 3 or 4 replacement it's crazy and i understand very frustrating!
I've had MBPs with the LG screen (9C67) which did not exhibit this problem, so I'd definitely say that the MBP I just received suffers from the yellowing issue.