Mr. Zuckerberg and the artist Ronen V.

If Airtime wasn't already star-studded enough, here's another celebrity who's excited to check it out. Mark Zuckerberg popped up as the New York online video artist Ronen V. was testing out the service's video-chat-a-stranger feature. (Interests: Facebook, Daft Punk, fencing. They both like Gary Vaynerchuk.) "I was still figuring it out, it was my first 'random' airtime chat," Mr. V. wrote in an email. "Once I realized who he was, I just thanked him for making facebook. After like 30 seconds he NEXTed me." Viral marketing stunt, or just trying out his buddy Sean Parker's new app? We wonder how many other Airtime users got Zuck-rolled today.