Everyone knows about Star Trek and the science fiction genre. Science fiction plays with future technologies that do not exist yet. While not everything in Star Trek has now been invented, when it comes to user interfaces, we are pretty close. We now have touch-screen, very small computers, voice commands and rich real-time 3d visualization (real life proof of this: the Star Trek Flat).
Well, Star Trek will need to update real fast. The computer industry is still rapidly evolving, and pretty soon, the post-Star Trek user interfaces might emerge. A great example is the Sixth Sense research project. This is a portable image recognition and projecting device, that provides in-context display and can be used using gestures, projected surface interaction, or simply holding objects in front of it. See this TED presentation for more information and some great demos. It will be interesting, when this becomes mainstream, how much of current UI frameworks can be reused to build the next-gen interfaces.