Overall -- my impression of the MacBook Air is mostly, 'eh'. Thin. Light. Likely exaggerated battery life (if you're just going to surf the web for 5 hours, you don't need this laptop to do that).

The multi-touch pad gestures felt a bit gimmicky when I watched the demo last evening.

I believe this is one of the undocumented gestures:

1. Start by Using your index finger, your pinkie, and the back of your palm and place them firmly on the pad.
2. Pinch your butt cheeks together while softly chanting “Apple”, (repeat at least 3 times)
3. Then in a quick twisty pinchy-slidy motion, press the C key to close the current window.

:)