Hi, I just discovered this by accident currently traveling and I know it's not directly related to Ubuntu, but many have been concerned about the lack of a kensington security slot on the Macbook Air, so I thought I'd mention this solution.
Do you know those white, combination/or card swipe personal safes that you often have on your room in cruise ships? I have a similar one here at a Holiday Inn at Destin, FL and....VOILA! The Macbook Air fits neatly inside one of these safes.
That's all... Frank B.