A company named Flash Fog Security has created a number of applications for using fog as a security system. They claim that the fast deployment of fog makes it a natural fit with the world of security, especially for stores or automobiles. The company can also combine the fog with powerful strobe lights to create, "An astonishing and instant blinding effect." I'm sure that's just what you were looking for. ;)

Compared to other defense mechanisms, fog works well because it doesn't ruin anything... Unless it accidently blows when you're driving your car. Have fun with that...