This is the HAV prototype Hybrid Airship. That means it's slightly heavier than air and it uses lift generated by forward motion to keep it in the air. This makes it much easier to handle when it's on the ground. The Lockheed P-791 is similar to this in concept but appears to not be so well designed aerodynamically.
HAV are one of the bidders for the Pentagon's "Long Endurance Surveillance Vehicle" (LEMV).
http://www.hybridairvehicles.net/
