I've just checked 5 display units in my Apple Store today, with my own iPad 3rd gen to compare.
Wow! I didn't imagine such a difference!

My unit is kind of yellow (but not washed out...) and in comparison, Apple Store unit are really pink/purple. Definitely a real difference here. Also, this purple tint make the screen dimmer in comparison with my Pad. Not sure colors are more "accurate": but neutral grey looks definitely different between both units.
In the store, the panel uniformity is (really) difficult to check! When the iPad is 50-60% brightness, you barely see a thing on the screen, so impossible to check that point easily on location... Even my iPad doesn't seems that bad over there (full brightness in a high luminosity place)

Pink/purple unit are clearly more similar to iPad 2 colorimetry (iPad 2 are used to display product informations: easy to compare) and display units need a higher brightness level comparatively to my own iPad (I'd say 75-80% = 60-65%).
Most display units are
from february and come from factory DQ (China - Foxconn refurbished?)... Don't know if that's of any interest.
I have an appointment at the genius bar thursday. I'll see what they think of the situation. I'm a bit anxious because the uniformity problem is difficult to check over there. Mine is note good, but gosh, I've seen really bad and ugly display units (... green and pink!) in another store, so... this is Roulette.
Thanks for the experience Apple. No more
day one purchase for me, I'm done.