For anyone uncertain about the MBA's incredible screen quality, the next time you visit Best Buy, Fry's or an Apple store open up System Preferences and choose Desktop&Screensaver and change the desktop pic to the darkest background of the Black and White options. The Air is unmistakably the best against the MB and the MBP.
If you visit a Best Buy they always have the Macbook line sitting side by side.
I've been to Best Buy and I've compared the old MBA with the new MBP and the new MBP was easily the best screen to my eyes, MBP>MBA>MB. The screen quality of the MBA is good, but the new glass screen of the MBP makes colors pop in an amazing way. Quality wise, the MBA screen and MBP screen are probably very similar but I think the reason the MBP looks so amazing is because of the glass glossy screen. When the new Macbooks were being announced I was really crossing my fingers for the glass screen and glass trackpad to make it over to the MBA and I was quite disappointed to see that it didn't happen.
Maybe it was too much effort for Apple to add the glass screen and trackpad, but its sure a disappointment to me. I would of traded power for portability, but the amazing screen on the MBP and the new trackpad closed the deal for me.
I did not try the black background as you say, but I tried various pictures and the new MBP was clearly ahead. It's possible the MBA has a screen that produces better blacks, but the MBP clearly wins overall color saturation and vibrancy.