You've spent the last several weekends hunting for the perfect lamp to brighten up that shadowy corner of the living room. When you finally bring it home and plug it in, the network of motion sensors and light meters in the house immediately senses the torchire and turns it on-but only if it's dark and you're in the room. And if you decide to swap it with the lamp in the bedroom, no problem: the network figures that out as soon as you're done.

In theory, linking together sensors, appliances and other devices so they can communicate and work together could make life easier and more productive. The reality-at least for now-is that setting up such networks is expensive and far from easy, especially if they involve thousands or even millions of components.