A decade ago, when I first got a cellphone, I sometimes would call my wife while walking home over the Brooklyn Bridge. (Yeah, it's a pretty neat commute.) Her reaction was always the same: "Why are you calling me? Is something wrong?" When I'd sheepishly say no, she'd point out that I could talk to her at home, and shoo me off the line posthaste.

At first I'd grumble about this -- didn't my wife grasp the wonders of the technological revolution? -- but pretty soon I came around to her way of thinking, and in doing so confronted...