It seems innocent at first: Fire up the search app on a new Android phone, and the interface asks if you'd like to activate Google Now. "Sure," you think, "Google already has my calendar, location, and contacts; what's one more thing?" Here's what: Google Now draws a distinct technological line. On the side you're on now, you tell your devices what you want to do. On the far side, the devices do the telling. Google Now is waiting for you over there. It's the first virtual assistant that truly anticipates your needs. All you have to do is opt in.