In recent weeks, New Yorkers have been using forwarded e-mails to coordinate "flash mobs," or not-so-random crowds that appear and dissipate within a matter of minutes. Is it performance art? The cutting edge of a new social movement? Or just an easy way to flummox carpet salesmen?

To protect the planned serendipity of each event, participants aren't told exactly what the mob is supposed to do until just before the event happens. For the most recent New York happening on July 2, participants passed around an e-mail telling them to assemble at the food court in Grand Central Station, where organizers (identifiable by the copies of the New York Review of Books they were holding) then gave mobbers printed instructions regarding what to do next.

The result: Shortly after 7 p.m., about 200 people suddenly assembled on the mezzanine level of the Grand Hyatt Hotel next to Grand Central Station, applauded loudly for 15 seconds, then left.
—Maureen Ryan, "All in a flash: Meet, mob and move on," Chicago Tribune, July 11, 2003

Organizing a "flash mob" basically involves e-mailing a bunch of people with instructions to show up at a certain place for a few moments, then disappear.

According to www.cheesebikini.com, salespeople in New York were a bit confused when there was a huge, instant gathering around a particular rug. The flash mobbers agreed to tell the salespeople they all lived together in a warehouse in Queens and were thinking of buying a rug. The crowd dissipated after precisely 10 minutes. Poof.
—Kim Lamb Gregory, "Briefs," Ventura County Star, July 1, 2003