] A type of wallpaper that prevents Wi-Fi signals escaping
] from a building without blocking mobile phone signals has
] been developed by a British defence contractor. The
] technology is designed to stop outsiders gaining access
] to a secure network by using Wi-Fi networks casually set
] up by workers at the office.

Very cool. Lots of potential for this kind of thing, I think.

Article: Stealth wallpaper keeps company secrets safe�| New Scientist