Stampede

Seems to me the problem here was that the laptops were mispriced:

Presented with a rare chance to get a used laptop computer for $50, a crowd of more than 5,000 showed up hours early yesterday at the Richmond International Raceway and -- when the gates finally were flung open at 7 a.m. -- turned into an unruly stampede, as people pushed, shoved and beat each other to get to the Apple iBooks. Elderly men and women were trampled and a girl's stroller was crushed.

:
"There was pandemonium at the gate where people rushed to get through," said H.W. Stanley Jr., police chief for Henrico County, where the event was held. The melee lasted about five minutes, and about 70 police officers eventually were called in to control the crowd, Stanley said. About 17 people were injured, including four who were taken to a hospital and treated for scrapes, bruises, heat-related problems and possible broken bones, authorities said.

Update: Looks like I beat Marginal Revolution to the punch, although they have a much more detailed post on the subject.