Also on par with current conversation. This is a photo I took in Iraq Mar '06. http://i.imgur.com/5tpV4RH.jpg clearly shows a glider/ultralight. I turned this photo and GPS marker in to my unit's S2 (intel guys.) They investigated and found out he was flying above convoys dropping grenades and homemade bombs. So, from a guerrilla warfare point of view hang gliders and/or ultralights are possible threat. Cheap, quiet, lightweight form of aerial combat and or surveillance.

HANG GLIDER FOR MILITARY APPLICATION *concept*

http://personal.mecheng.adelaide.edu.au/maziar.arjomandi/Aircraft%20Design%20Projects/2010/HANG%20GLIDER%20FOR%20MILITARY%20APPLICATION.pdf