Could the hack have happened without an organization like THA? Bigler thinks not. "Our group had done a number of hacks, and each hack raised the bar on detail, complexity," he says. Number 221 agrees: "What [THA] does is promote the long-term memory of the hacking community so that lessons are cumulative rather than everyone starting from scratch."

To many members, including number 221, secrecy is essential to the association's existence. "Plausible deniability is important for the administration," explains 221. "If the membership were known and the hacks were publicly credited, the Institute would know who to punish."

This penchant for secrecy helps explain the group's refusal to take credit for its hacks. "After all, an organization that no longer exists couldn't possibly be pulling new hacks," adds the group's current leader, who is known as the chancellor.

And then there's the matter of hurt feelings. "Nonmembers have been involved in hacks spawned by THA members," the chancellor says. "To then claim such a hack as 'a THA hack' is wrong, given the contributions by those who are not members."

The curious result is a group that disavows its greatest accomplishments. This shadowy mode of operation also leads to a mystique surrounding the organization, perhaps best summed up by Deborah Douglas, MIT Museum curator of science and technology, who calls the group "MIT's version of Skull and Bones." It's an august comparison--a 173-year-old Ivy League club with ties to both presidential candidates in the 2004 election and a 25-year-old group whose idea of a good time is climbing around on rooftops. The chancellor dismissed the comparison, saying, "The only real similarity is an element of secrecy."

Yet one wonders. Looking at the membership list, one sees physicians, an attorney, professors--including a distinguished member of the MIT engineering faculty--a national television personality, a high-level executive for a major European bank, and an entrepreneur who founded a $10 million software company. Maybe the comparison is not so far-fetched, after all. Members of this underground group credit it as playing a major role in their success. Let's hope it remains "defunct" for another 25 years.