There's no way anyone could possibly mistake Northrop Grumman's X-47B for anything like a normal aircraft: during its first wheels-up test flight a few weeks ago, the unmanned jet fighter looked uncannily like a UFO.
There are all kinds of advantages to a robotic fighter jet: it can be smaller, lighter, faster, and more efficient, carrying more useful payload for longer ranges. Since it doesn't have to worry about keeping a fragile human pilot alive and comfortable, the X-47B can be sent on extended missions lasting for as long as it has fuel, it can give over internal areas that would otherwise be housing a cockpit to weapons or surveillance systems, and it can pull acrobatic maneuvers that would turn a human pilot into a quivering pulp.
At first, the X-47B will be flown remotely (like a Predator drone), but longer term, the idea is for the aircraft to be completely autonomous, although hopefully someone will have the forethought to install a kill switch on it somewhere. These pics show the first "wheels-up" test of the X-47B, which allowed engineers to get a much better sense of its aerodynamics and cruise mode flight characteristics.
This second pic gives an especially good view of the X-47B's tailhook, which it's going to use to autonomously land on aircraft carriers, a feat which even the best human pilots find to be challenging, at best. But this is exactly the sort of maneuver that computers and robots excel at, and the X-47B should be performing its first carrier landing sometime in 2013.