I'm a "thin" junkie... The new Macbook makes the Air look thick like the pro :3.
From apple.com, the macbook is .14 to .52 inches thin, and the 13" air is .11 to .68 inches thin. So the air goes from just a hair thinner at its thinnest to a few hairs thicker at its thickest. They're all but equal in that respect. Lighter, yes, by .93 lbs, but thinner? Only by the tiniest of margins.