Open source intelligence

Definition
Open source intelligence is an approach to intelligence gathering that involves collecting information from publicly available sources and analyzing it to produce usable intelligence. The term "open source" is not related to open-source software. (See the Wikipedia article for more.)

Issues
Questions:
 * Is it really such a new idea to take this seriously?
 * How naive it is to see this as the major source of intelligence info?

Related thoughts:
 * In the documentary movie The Fog of War, McNamara laments his lack of understanding of Vietnamese history and nationalism at the time of the Vietnam War, when he was the US Secretary of Defense. It might appear to a casual viewer that he had been completely unaware of the facts, with tragic but unintended consequences. Yet at the time of the war and even before its escalation in the mid-1960s, some people were putting these arguments forward forcefully. For example, John Kenneth Galbraith (then the US Ambassador to India) in a private letter to US President, John F Kennedy, warned against mistaking nationalism for hardline communism (is that correct? need to check the details of this) or supporting an undesirable government in the South Vietnam. So, in this case, it appears that the knowledge was widely available, but ignored or rejected by the strategists in Washington.
 * Bali Bombing & the Australian government's travel advice: Islamists had already carried out a number of nightclub bombings in Jakarta. The warning signs were there but apparently ignored by Australia's DFAT (Department of Foreign Affairs and Trade) which issued travel advice for Indonesia that failed to mention such dangers.
 * Boxing Day tsunami: A Thai scientist had lobbied for a better warning system, but the government attempted to silence him, apparently not wanting to raise fears and perhaps discourage tourism. Could an active and open network and forum for discussion (such as Issuepedia?) led to more prominence for such warnings, leading to timely action? Or would sensible warnings be drowned out amidst less sensible fears and conspiracy theories? (Note that it can take a lot of judgment and research to tell if a warning is sensible. Even hindsight is not enough to decide what was sensible, as the potential disaster may not happen, even if it was sensible to warn of the possibility.)