The camera is the camera. Snow Leopard doesn't change the fact that the Air's iSight is only VGA (640x480). In contrast, the MBP line has a 1.3MP iSight (or about 1280x1024), or more than 4x the resolution.
Snow leopard does, however, increase the compression of the video, which means that you'll get a better picture with less bandwidth (about 2/3 less - 900kbps -> 300kbps).