FAA has approved several bio-aviation fuels. Just did another one: [www.flyingmag.com]. Presumably, some of these things would work in ordinary diesels too, and some railroads have in fact experimented with bio-diesel. Anyway, if the airlines really get moving on this, could it appease the Corn Lobby without moving gasoline to E15? Certainly, aircraft use a lot of fuel ... and so do locomotives. There is, of course, the cost (Real Diesel is cheaper, as is Real Jet Fuel if proper hedging is done or (like Delta) you own the refinery).