British defense contractor BAE Systems has developed a stealth <A HREF="http://zdnet.com.com/2100-1103_2-5241808.html?tag=zdnn.alert">wallpaper designed to stop electronic eavesdropping</A> on Wi-Fi networks. The company has produced panels designed to prevent outsiders from listening in on companies' Wi-Fi traffic but let other traffic through, including radio and mobile phone signals.