Now here's a solar/electric powered UAV that shouldn't affect air
traffic too much:

http://www.avinc.com/pr_detail.asp?ID=63
AeroVironment Awarded Contract for Development of Global Observer
Stratospheric Unmanned Aircraft System
9/26/2007

MONROVIA, Calif., Sept. 26, 2007 – AeroVironment, Inc. (AV)
(NASDAQ:AVAV), a leader in unmanned aircraft systems and efficient
electric energy systems, today announced that it has received a
contract from the United States Special Operations Command
(USSOCOM) for the development and military utility assessment of
its Global Observer unmanned aircraft system (UAS). This contract
initiates a Joint Capabilities Technology Demonstration, or JCTD.
The JCTD is sponsored by multiple U.S. government organizations.
The contract calls for the development of up to three Global
Observer aircraft over the next three years to demonstrate the
ability to operate in the stratosphere for up to 7 days without
landing. The basic contract, which will be funded under a
cost-plus fixed-fee arrangement, provides for the development and
delivery of the initial Global Observer aircraft, and is valued at
approximately $57 million. The contract also includes options for
the development and delivery of up to two additional Global
Observer aircraft, resulting in a potential contract value of $108
million. ...

It's good to see AeroVironment's continued success despite the recent
loss of its founder.