University researchers use Second Life to study urban planning and create a meeting place for people with Aspergers syndrome, a neurobiological disorder, among other projects. The Department of Homeland Security has used the online world to develop emergency response training.

"Seven years ago, people would ask, 'Where's your Web site?'" Paffendorf says. "Now it's, 'Where's your island, where's your virtual world?' It wasn't like that a year ago."
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