Ubiquitous computing is "roughly the opposite of virtual reality. Where virtual reality puts people inside a computer-generated world, ubiquitous computing forces the computer to live out here in the world with people. Virtual reality is primarily a horse power problem; ubiquitous computing is a very difficult integration of human factors, computer science, engineering, and social sciences". On this site are so of the most intelligent and ahead-of-their-time essays I've read. Ubicomp is a manifesto for what we should be building right now. And these guys have thought of it all already. Picking out two in particular:

The Coming Age of Calm Technology (1996) gives the wonderful example of the Dangling String that makes invisible ethernet traffic visible and understandable.

Building Invisible Interfaces (1994) powers its way through the nature of interfaces and the problems faced by ubicomp (where else have you seen a calculation of the maximum bandwidth available based on the surface area of the Earth?). And the ideas! In an energy scare world: "pushback to user what is hard or easy. color every button according to power-cost of pressing it" (in the real world!).