The British Telecom's Security Research Centre recently carried out a joint security study with the University of Glamorgan in Wales, Edith Cowan University in Australia and Longwood University in the US. They bought 300 hard drives on eBay, originating from the US, UK, Germany, France and Australia. A proportion of the drives were formatted, but none were done with a destructive format and many contained easily recovered files.
100 of the drives turned out to contain extremely confidential information such as building blueprints and launch procedures for the Lockheed Martin's surface-to-air missile defense system. Other drives included everything from medical records, x-ray images, patient photos, confidential letters and confidential corporate information detailing a 50 billion currency exchange.
So the moral of the story is that if you're selling or throwing out your old hard drive, you better remember to perform a destructive, all-zeroes format.
via Daily Mail