When Apple’s iPhone hit the streets last year, it introduced so-called multi-touch screens to the general public. Images on the screen can be moved around with a fingertip and made bigger or smaller by placing two fingertips on the image’s edges and then either spreading those fingers apart or bringing them closer together. The tactile pleasure the interface provides beyond its utility quickly brought it accolades. The operations felt intuitive, even sensuous. But in laboratories around the world at the time of the iPhone’s launch, multi-touch screens had vastly outgrown two-finger commands. Engineers have developed much larger screens that respond to 10 fingers at once, even to multiple hands from multiple people.