One of the reasons I sold my Macbook Air Rev B was due to the low isight res during video chat. Snow Leopard however from what I heard increases the quality. Has your video chat sessions improved in quality with Snow Leopard?
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).
