I found this posting via search, as my new iPad2 64gb Wi-Fi also has a yellowish screen. I noticed immediately on switch on as I already own a 32gb that I'm upgrading from, and that has a blueish, clearer, brighter display. Putting them side by side at full brightness is the best way to see the difference, and I decided I wouldn't live with it and called Apple.
They didn't acknowledge a known issue, nor wanted to comment on any of these forum postings (there are a couple of similar ones to this) which describe the issue exactly.
They were very helpful though, and when I bleated that I didn't want my sub-24 hours old one replaced out of their refurb stock, they transferred me to another department and they agreed to send a new retail box out.
I may even have chance to compare all 3 side by side before the courier collects my dodgy one, and the guy said he thought there was less than a 1% chance of me experiencing the same issue again.
Hmmm... I don't know about that. Unless he has the means to select "Blue stock", and just didn't want to admit anything to the public that Apple know they have an issue here.
All in all I was very pleased with their polite attitude, but I did feel like I was explaining a fault to their ears for the very first time, and I would have prefered them to acknowledge it.
I'll post my results here in a few days.