The second issue, which is being conflated with the first, is characterized by light bleeding through from the outer edges of the LCD panel.
The first problem reported by some is a yellow patch on the LCD. The second is this light bleeding problem, which can be a big one or a small one.
It’s a big problem if the LED-based backlight unit (BLU) is defective. I’m fairly sure the BLU is located on the bottom of the LCD in portrait orientation and that’s where the problem seems to be.
Let’s hope it’s a small problem though: someone at Foxconn forgot to put some black tape around the bottom bezel of the LCD module. Just a wild guess on my part based on what I’ve seen on my 17-inch MacBook Pro when I took the cover glass off: there were a lot of black tape around the bezel of the LCD to prevent light leakage.
Regardless, if you have an iPad 2 that has light bleeding take it back and get a new one. Hopefully you bought an iPad 2 at the Apple Store because service is heads and shoulders above anywhere else. Even if you have to wait a light bleeding LCD will be extremely annoying and you don’t want to be living with one for a long time.