I speculated a few years ago about the potential of having a projector with you in your pocket. By that time, it was not yet possible to run presentations off your smartphone. Things have changed now and devices like the Popvideo pico projector for iPhone (comic sans alert) might be on their way to becoming a replacement for the crappy VGA corporate overhead projectors in conference rooms (the keynote hall is still too much of a challenge). I think there will never be a real market for projecting confidential business presentations on the walls of public places such as cafes. It might spur a new generation of graffiti or performance artists though...