I have an late 08 unibody Mbp and a 11 mba, I have noticed the glass trackpad on the air is much closer to the glass on an iphone in the way your finger reacts to it... the least bit of moisture and your finger doesn't glide as easily. On the pro it seems to have more of a coating to allow for smoother use under these normal conditions (humidity). Has anyone else noticed this? bottom line the air trackpad almost seems more polished.