Judging by published photos, postings, and personal experience, the severity of this problem varies between "difficult for an average human to detect" all the way to "difficult for an average human to ignore."
Here we go again. It's this know-it-all rhetoric that gets to me, the notion that it's impossible that there are yellow tinge-free iMacs with uniform color out there because of their own experiences and that of their color-elitist online brethren.
In regards to color uniformity on the display I don't consider myself to be an "average human". I am quite familiar with gradients, even the slightest. I went through the mill with them sending back my mid-2007 24" iMac for just that reason. I know what a yellow tinge looks like, and for the 5000th time I acknowledge and sympathize with those that are experiencing them but the display on my own i7 doesn't have one, period.
When you say it exists on ALL 27" panels and that some people just can't recognize it or don't have a discerning enough eye to see it it's beyond BS. It's insulting. The same goes for accusations that it's Apple fanaticism to deny it or outright lying/ignorance. Noone's accusing those suffering with bad displays of these things. Try to offer the same respect, please.