By this fall, more than 3,600 members of the intelligence services had contributed a total of 28,000 pages. Chris Rasmussen, a 31-year-old “knowledge management” engineer at the National Geospatial-Intelligence Agency, spends part of every day writing or editing pages. Rasmussen is part of the younger generation in the intelligence establishment that is completely comfortable online; he regularly logs into a sprawling, 50-person chat room with other Intellipedians, and he also blogs about his daily work for all other spies to read. He told me the usefulness of Intellipedia proved itself just a couple of months ago, when a small two-seater plane crashed into a Manhattan building. An analyst created a page within 20 minutes, and over the next two hours it was edited 80 times by employees of nine different spy agencies, as news trickled out. Together, they rapidly concluded the crash was not a terrorist act. “In the intelligence community, there are so many ‘Stay off the grass’ signs,” Rasmussen said. “But here, you’re free to do what you want, and it works.”

By the late summer, Fingar decided the Intellipedia experiment was sufficiently successful that he would embark on an even more high-profile project: using Intellipedia to produce a “national intelligence estimate” for Nigeria. An N.I.E. is an authoritative snapshot of what the intelligence community thinks about a particular state — and a guide for foreign and military policy. Nigeria, Fingar said, is a complex country, with issues ranging from energy to Islamic radicalism to polio outbreaks to a coming election. Intellipedia’s Nigeria page will harness the smarts of the dozen or so analysts who specialize in the country. But it will also, Fingar hopes, attract contributions from other intelligence employees who have expertise Fingar isn’t yet aware of — an analyst who served in the Peace Corps in Nigeria, or a staff member who has recently traveled there. In the traditional method of producing an intelligence estimate, Fingar said, he would call every agency and ask to borrow their Africa expert for a week or two of meetings. “And they’d say: ‘Well, I only got one guy who can spell Nigeria, and he’s traveling. So you lose.’ ” In contrast, a wiki will “change the rules of who can play,” Fingar said, since far-flung analysts and agents around the world could contribute, day or night.

Yet Intellipedia also courts the many dangers of wikis — including the possibility of error. What’s to stop analysts from posting assertions that turn out to be false? Fingar admits this will undoubtedly happen. But if there are enough people looking at an entry, he says, there will always be someone to catch any grave mistakes. Rasmussen notes that though there is often strong disagreement and debate on Intellipedia, it has not yet succumbed to the sort of vandalism that often plagues Wikipedia pages, including the posting of outright lies. This is partly because, unlike with Wikipedia, Intellipedia contributors are not anonymous. Whatever an analyst writes on Intellipedia can be traced to him. “If you demonstrate you’ve got something to contribute, hey, the expectation is you’re a valued member,” Fingar said. “You demonstrate you’re an idiot, that becomes known, too.”

While the C.I.A. and Fingar’s office set up their wiki, Meyerrose’s office was dabbling in the other half of Andrus’s equation. In July, his staff decided to create a test blog to collect intelligence. It would focus on spotting and predicting possible avian-flu outbreaks and function as part of a larger portal on the subject to collect information from hundreds of sources around the world, inside and outside of the intelligence agencies. Avian flu, Meyerrose reasoned, is a national-security problem uniquely suited to an online-community effort, because information about the danger is found all over the world. An agent in Southeast Asia might be the first to hear news of dangerous farming practices; a medical expert in Chicago could write a crucial paper on transmission that was never noticed by analysts.

In August, one of Meyerrose’s assistants sat me down to show me a very brief glimpse of the results. In the months that it has been operational, the portal has amassed 38,000 “active” participants, though not everyone posts information. In one corner was the active-discussion area — the group blog where the participants could post their latest thoughts about avian flu and others could reply and debate. I noticed a posting, written by a university academic, on whether the H5N1 virus could actually be transmitted to humans, which had provoked a dozen comments. “See, these people would never have been talking before, and we certainly wouldn’t have heard about it if they did,” the assistant said. By September, the site had become so loaded with information and discussion that Rear Adm. Arthur Lawrence, a top official in the health department, told Meyerrose it had become the government’s most crucial resource on avian flu.

The blog seemed like an awfully modest thing to me. But Meyerrose insists that the future of spying will be revolutionized as much by these small-bore projects as by billion-dollar high-tech systems. Indeed, he says that overly ambitious projects often result in expensive disasters, the way the F.B.I.’s $170 million attempt to overhaul its case-handling software died in 2005 after the software became so complex that the F.B.I. despaired of ever fixing the bugs and shelved it. In contrast, the blog software took only a day or two to get running. “We need to think big, start small and scale fast,” Meyerrose said.

Moving quickly, in fact, is crucial to building up the sort of critical mass necessary to make blogs and wikis succeed. Back in 2003, a Department of Defense agency decided to train its analysts in the use of blog software, in hopes that they would begin posting about their work, read one another’s blogs and engage in productive conversations. But the agency’s officials trained only small groups of perhaps five analysts a month. After they finished their training, those analysts would go online, excited, and start their blogs. But they’d quickly realize no one else was reading their posts aside from the four other people they’d gone through the training with. They’d get bored and quit blogging, just as the next trainees came online.