Google.org, Google's philanthropic arm, has launched a service to help medical experts and the public track the incidence of influenza across the United States.Google Flu Trends presents a map of current flu activity throughout the nation.

The service assumes that the flu-related Google searches correlate with the number of people affected by the flu at any given time and a graph of CDC flu reports and flu-related Google searches supports that assumption.

"We have found a close relationship between how many people search for flu-related topics and how many people actually have flu symptoms," Google's Web site explains. "Of course, not every person who searches for 'flu' is actually sick, but a pattern emerges when all the flu-related search queries from each state and region are added together. We compared our query counts with data from a surveillance system managed by the U.S. Centers for Disease Control and Prevention (CDC) and discovered that some search queries tend to be popular exactly when flu season is happening. By counting how often we see these search queries, we can estimate how much flu is circulating in various regions of the United States."

What's remarkable about Google's flu search data is that it's timelier than CDC data. The Google.org Web site claims that Google's tracking system has been able to estimate national flu levels accurately, two weeks before the CDC.

John Battelle, author of a book about Google called The Search, described the company as a "Database of Intentions." It's that and more, a database of symptoms, connections, and secrets hidden in plain sight.

Google has become a mirror of our collective intelligence, our private folly, and the health of humankind. It becomes more richly endowed with information every day and will be mined more thoroughly for it.

I wonder whether anyone at Google monitoring search trends saw the recent financial market collapse coming before it became obvious to the public.

If Google ever wants to make some extra money, I suspect there are a lot of people who'd pay well for query-driven stock trading.