From the New York Times:
Chris DiBona’s work as manager of open-source programs for Google takes him on the road, where laptops grow heavier with every gate he passes in the airport. So he has been experimenting with piecing together the ultimate lightweight PC.
At the core of his ensemble is the OQO-01, a full-featured PC running Windows XP that is not much bigger than a pack of 3-by-5 index cards. It’s measured in ounces (14), not pounds.