Evolution of Text Input Devices

This recent story on Slashdot about the release of the AlphaGrip AG5T got me thinking about the state of computer input devices today. While I find the AG5T a welcome advance over the traditional flat keyboard, I have to wonder why we are still stuck on this old model of generating text by hacking out a single character at a time. Is it possible to design an input device capable of generating syllables, or even whole words, in a single stroke? Would human minds be capable of productively using such a device?