There's also this other Kensington model:

http://www.kensington.com/html/3722.html

It works with a variety of laptops including Apple, and adds an AC adapter to the feature set of the other Kensington. That means you only carry this one power adapter, instead of one for the plane and one for the hotel room when you get there. Probably worth the extra US$30 if you travel frequently with your computer.