Last July the U.S. Army issued a manual, Army Techniques Publication 2-22.9, on using open source (mainly searching the Internet) intelligence. Also called OSINT, the troops have been using the Internet for intelligence work for over a decade. The publication of ATP 22.9 is a way for the senior army leadership to say, "message received and understood." ATP 22.9, despite all the useful tips it contains, won't go far in helping the many soldiers already using the Internet but it will be useful in convincing their bosses that much useful stuff can be obtained from the Internet.
While the U.S. intelligence community officially recognized the importance of OSINT (Open Source Intelligence) back in 2004, it was years before there was a lot of enthusiasm from the top brass for using this growing source of information.
The Internet has made OSINT a really, really huge source of useful intelligence. It's not just the millions of gigabytes of information that is placed on the net but the even more voluminous masses of message board postings, blogs, emails, and IMs (instant messaging) that reveal what the culture is currently thinking. It was corporate intelligence practitioners who alerted the government intel people to the growing usefulness of Internet based data. Corporations have developed, over the last few decades, a keen interest in gathering intel on competitors, new markets, and all manner of things that might affect them. This "competitive intelligence" (or corporate spying) became big business. The Internet has made this a much more useful exercise.
However, corporate intel specialists were concerned that government agencies, especially the CIA, were not taking sufficient advantage of OSINT. Part of the problem was cultural. The intelligence agencies have always been proud of their special intel tools, like spy satellites, electronic listening stations, and spy networks. Most of these things are unique to government intelligence operations. People who use this stuff tend to look down on a bunch of geeks who simply troll the web. Even when the geeks keep coming up with valuable stuff, they don't get any respect. The fear was that some foreign countries were exploiting OSINT more effectively than the United States. No foreign intel agency will admit to this but there are indications that some nations are mining the Internet quite intensively and effectively.
This fear grew as China, Russia, and other nations were caught using the Internet for direct espionage (hacking into other nations' networks). While examining that threat it was discovered that the heavy use of OSINT was part of the hacking operations. Thus over the last five years the CIA and other major intel agencies got more enthusiastic about OSINT, and this made it easier for Internet-savvy army leaders to get ATP 22.9 into print.