Always a Market for Good Ideas -- DARPA

Publicity is beginning to emerge about DARPA's latest cool program, a "robotic hummingbird" they call an Ornithopter. In actuality, it is a nano-UAV whose largest dimension is about 4 inches with flight characteristics more like a bird than an aircraft. This is significant because, frankly, birds are vastly more flexible in flight than fixed wing, or even rotary wing aircraft.

The nano-UAV will be able to provide reconnaissance and surveillance in urban environments -- listening and recording, or even depositing spy devices and then leaving them in place.

Yea, the bird looks pretty hokey but what's important is that it is quiet and can just alight in a tree and stay put. No one would notice it then.