In the case of Vulture, the idea is to achieve a platform with the good qualities of both satellites and aircraft, hopefully with none of the downsides of either. According to a DARPA statement issued yesterday:

Vulture technology enables a re-taskable, persistent pseudo-satellite capability in an aircraft package. The technology combines the key benefits of an aircraft (flexibility & responsiveness, sensor resolution, reduced transmit/receive power, affordable deployment) with the benefits of a satellite (on-station persistence, no logistics tail, zero emissions, energy independence, minimal fleet size, absence of in-country footprint). The system has potential in numerous roles: operation as a single platform, as a formation of multiple aircraft or as a constellation providing infrastructure augmentation or recovery.
http://www.theregister.co.uk/2010/0..._vulture_order/

http://www.foxnews.com/scitech/2010...raft-fly-years/