Care of the Belmont Club, comes this vid of a remotely-operated quad-rotor platform. Some truly impressive software enables it to execute maneuvers which are downright balletic in their nimbleness. Check it out.
This is some pretty extraordinary stuff, and begs the question of why the frack we don't have piloted vehicles with this sort of architecture. Their superiority over conventional high, open-rotor designs is obvious, in terms of maneuverability and range of safe operating environments. Four shrouded ducted fans could propel a vehicle, for example, through forest canopy in ways that would turn a conventional helo into a shrieking mass of falling metal and several high-velocity flying swords. Sure, you couldn't autorotate in the event of an engine failure, but you could probably compensate for the loss of one engine, and a ballistic parachute system would be simpler to implement than in a typical rotorcraft for catastrophic faults.
All that aside, the possibilities for reconnaissance and surveillance (not to mention kinetic urban engagements) are just as obvious. Armed with ordnance and/or cameras and sensors, one or ten of these little suckers would vastly increase the potential situational awareness of troops in complex areas of operation. They could scoot through windows or doors (or tunnel hatches), and scope out those pesky blind corners with the greatest of ease. Packing a grenade, they could be very effective in breaking the ice...
Of course, on that latter point, Richard Fernandez at the above-linked BC post has some things to say about the law of unintended consequences with respect to the current administration's efforts to close both prominent and clandestine facilities for the holding of captured baddies. In essence, by foreclosing on options for detention and interrogation of high-value targets, the emphasis has, perforce, moved decidedly in the direction of liquidation (everything must go!). Despite international hand-wringing on the "legality" of targeted assassinations via drone strike, there really is little alternative for dealing with those who draw breath all-but solely for the purpose of doing us harm.
Come hellfire or high-waterboarding, somebody is going to be offended by our efforts to defend ourselves against murderous miscreants. There is no simple solution to the dilemma. It is at least useful, however, to reflect on the distal implications of our decisions when it comes to fighting our foes.
After all, as the video so clearly shows, thrust in any given direction must be balanced by opposing counter-thrust. We really don't have all that much room to maneuver.