1. it weighs 3 lbs
2. so thin (under an inch at its thickest), it fits into a large department manila envelope (ok, that's what the promo ad showed)
3. multi-touch trackpad (kinda like the iPhone)
4. 13.3 inch backlit LED display
5. full size, backlit keyboard
6. I love mac. I think non-mac users are crazy.
Only drawback for me - no optical drive, but the demo guy says you can insert a disk into a computer with optical drive, then the MacBook Air wirelessly connects to that computer and downloads/installs from the optical drive. (Does that make sense? It sort of makes sense to me Sorry if I explained it weird.) This just assumes you live wirelessly through and through - rent movies from iTunes, for example.
Sticker price: $1,799.
PS - I didn't mean to omit the VERY important eco-consciousness of this product. (Plus, Green Base comments more coherently than I did on the lack of CD drive.)