Some grandparent enthusiasts say this latest form of virtual communication makes the actual separation harder. Others are so sustained by Web cam visits with services like Skype and iChat that they visit less in person. And no one quite knows what it means to a generation of 2-year-olds to have slightly pixelated versions of their grandparents as regular fixtures in their lives.

But at a time when millions of people around the world are beginning to beam themselves across the ether, the Web cam adventures of the nursery school set and their grandparents offer a glimpse at what can be gained — and what may be lost — by almost-being there.

But the powerful illusion of physical proximity also sharpens their ache for the real thing. “You just wish you could reach out and cuddle them,” said Ms. Pierce, a nursing professor. “Seeing them makes you miss them more.”