The revelation of a new stealthy version of the U.S. Black Hawk helicopter (an MH-60) during the May 2nd raid that killed Osama bin Laden, reminded everyone that secrets can still be kept, even in an open society like the United States. But if the MH-60 had not crash landed (due to unexpected climatic conditions) during the bin Laden raid, the new stealth design would still be a secret, or a unsubstantiated rumor.
But once it became obvious, via wreckage left behind, that the new helicopter model existed, the search was on for evidence of where and how it was developed. Using Google as the primary tool, one could discover that the manufacturer of the MH-60, Sikorsky, had bought a company that specialized in stealth, and customizing aircraft. Sikorsky was also one of the developers (with Boeing) of the cancelled RAH-66 Comanche helicopter, which was designed to be stealthy.
But it got really interesting when you used Google Earth to check out airports in northern New York, where Sikorsky does development work. There you find that several airports have security blocks on them (something governments can request from Google). Thus recent, or complete, satellite photos are not available for those places.
This is not to say that a foreign spy could not just drive by and use a cell phone camera (which is where most of those pix of new Chinese aircraft come from). Or you could set up more powerful equipment in a nearby house, and stake out the airport or Sikorsky facility. But spies typically don't share with other journalists. So while China or Russia may have known about the stealthy MH-60, most Americans did not.