Russian Spies used Steganography
The FBI arrested 11 suspected Russian spies for passing U.S. information to Russian spy agents using wireless networking and steganography.
Steganography is the process of writing hidden messages in such a way that no one, apart from the sender and intended recipient, knows of the existence of the message, a form of security through obscurity. The message can be hidden in pictures, text and many different forms.
For more on this story please refer to the links below:
The Economist – http://www.economist.com/node/16486569?story_id=16486569
Wired – http://www.wired.com/dangerroom/2010/06/alleged-spies-hid-secret-messages-on-public-websites/
Dark Reading – http://darkreading.com/insiderthreat/security/encryption/showArticle.jhtml?articleID=225701866
Linux Security – http://www.linuxsecurity.com/content/view/152728/169/