So I just spent an hour at my local Apple Store (Apple North Shore - Peabody, MA). Here is what i saw:
1) There were two MBAs - a new Rev B, 1.86GHz SSD and an older Rev A, 1.6 HDD. The Rev B had lines - faint, but you could see them. The Rev A was next to it and here was definitely a difference. The Rev A screen was clearly line free. I ran the test images found on page 4 of this thread. both images passed, but interestingly, the second/right image had a pulse-like flicker on the Rev B where the split ran down the middle of the image. I loaded the same image onto the Rev A and it displayed it rock solid. No flicker.