This augmented reality demo (thanks Dorian) is astounding. What looks like a window is actually a live video feed of what would be seen through it, augmented with 3d shapes drawn on with a stylus. Imagine this with eye-glasses.
(And talking of glasses and augmented reality: How about if scattered around were the equivalent of blue-screens, except they were filled with Java code, and your glasses had a JVM built in which would run the code with the output pasted over the real-life code? A newspaper article could end with a code snippet that would make a network connection to fetch live replies to a conversation thread; another piece of code could draw a keyboard and interpret the movement of your fingers and send the message back to the server. Why wait for mass-production of intelligent paper when a single instance per person of smart-client eye-glasses with OCR would do?)