The hackers didn't warn local authorities of the cannon's arrival, but they wanted to assuage any concern that might be provoked by the appearance of a working gun in the heart of campus. (Fleming House regularly fires blanks from the cannon at graduation.) So they sent an explanatory e-mail to David Barber, an assistant officer in the Environment, Health, and Safety Office's safety program, and to MIT's police and facilities departments. "The hackers know who to send messages to," Barber says, "and when the message is accompanied by photos and detailed documents about the nuts and bolts of the event, then we find them very reliable."

The gun's appearance caused a sensation, with such high-profile media outlets as National Public Radio and the London Times reporting on it. That it appeared at the beginning of Campus Preview Weekend didn't hurt, either. "We made sure admissions office tours stopped at the cannon," says ­Stuart Schmill, associate director of the admissions office.

Meanwhile, Fleming House students began organizing an effort to retrieve the cannon. They contacted alums and had received nearly $8,000 in contributions, according to Caltech vice president Tom Mannion, when the school president decided that Caltech would foot the bill. Two dozen students flew with Mannion to Boston, where--after proving ownership to the MIT Campus Police--they were allowed to tow the cannon away. After the cannon was safely secured on a tow truck, MIT students threw an impromptu barbecue for the Caltech contingent, during which students shared stories about the cannon's cross-country trek. The retrieval set off even more media coverage, with most major television networks and even ESPN joining in.

Shortly after Caltech recovered the gun, Douglas hosted an unusual meeting at the MIT Museum with what she cryptically refers to as "a group of individuals who seemed terribly interested" in the cannon hack. "This is the first ‘21st-century' hack," she concludes. "Its style and mode of organization--a very large group, highly organized, with careful planning, subcontracting work, and interest in public relations--makes it qualitatively different from earlier hacks."

One hacking tradition, however, remained inviolate. "The humor of this hack," says Douglas. "That quality is one it shares with its predecessors."

[For a timeline of the Caltech cannon hack, click here.]