Looks like my 500m, about 2 years old now, is exhibiting some of the reddish tint in black areas that others on these boards have reported. I just noticed this yesterday: my 500m was recently repaired (A-board replaced and a few other components, I think) after I fried it by dropping one of the 500m's external speaker wires onto a surge protector (be careful with those wires!). I suspect that the red-shift was present on my 500m before the repair, and that I am only noticing it now because I was hunting for flaws after the extensive repair.
Regarding the red shift, I have noticed what several others have said: the empty, black areas of the screen (especially the blank aspect-ratio bars) appear slightly red instead of deep, dark (nearly black) gray. It seems most pronounced on the lower right-hand side. I cannot detect red at all in any kind of material other than dark, blank screens and black bars. I did not know anything about this kuro/500m red shift phenomenon until today when I searched for "500m red tint" in this forum, so I don't think that it's my imagination. I don't think that this reddish tint was present when I first bought the TV 2 years ago (back when I was hunting for every possible flaw), but who knows.
Anyway, not a big deal, and the picture is still miles better than my Panny p50g10, but as others have said, it seems that some of these sets aren't as flawless (over time, anyway) as the early raves indicated.