I was just reading this fabulous blog post that I first spotted in Vinod Khosla's Twitter stream.
Matthew Devost: 23 Devices My iPhone Has Replaced
And I am thinking, the next breakthrough needed is a napkin keyboard. The smartphone's screen size is big enough. You could compose a full fledged document on it. But there is just something about the keyboard. People want to do the Qwerty thing on a keyboard whose size can not really be reduced.
The napkin keyboard you should be able to fold and put away. It should talk wirelessly to your phone, tablet. This would be swell for travel. This would eat into the Macbook Air. A napkin would be more airy, for lack of a better word.