I wanted to point out, as I already have in other threads, that I both bought a Week 37 Touch from a retail Apple Store, and also received a Week 38 Touch pre-ordered from Apple Store Online.
If I hadn't done a side-by-side comparison, I would have thought that my Week 37 was "perfectly fine", except for heavy blacks. I didn't have much noticeable negative effect, and compared to the "horrible negative effect" screenshots that have been floating around, my Week 37 looked golden.
Upon examining the Week 38, I now realize that the Week 37 is definitely, absolutely a bad screen, even though I never would have thought so otherwise. The level of shadow detail and definition in "blacks" has unmistakably improved in the Week 38.
Not to say that it's surely true for anyone else, but I think there are many people who are assuming the Week 37 screens are good simply because they have a) only seen screenshots that display only horribly extreme cases of bad screens and b) they haven't had a chance to compare them to Week 38s.
~ $0.02