Okay, here is my take:
We know it isn't a meteor. If it were, there would be some kind of physical damage to the lamp. If it was something that was so small as to not show any obvious damage, then it would not have been travelling fast enough to move that far in such a short amount of time and strike with such velocity by the time it reached the ground.
This can't be a contrail shadow, the sun isn't in the right spot. Plus you would see the line of the contrail on the ocean.
This can't be the shadow from the explosion of the lamp, it would widen as it went to the sky, which it does not do. Plus, the intensity of the flash is nowhere near enough to cast a shadow like that into air as clear as that. If it was, it would most certainly overexpose the CCD in the camera and you would not see any color, it would just be a very white flare. Plus, if it was the shadow, then the entire rest of the picture would brighten EXCEPT for the shadow during that frame. The differential picture would show difference everywhere else except the shadow.
I find it hard to believe that this is a bug. The white arcs by the lampost are too sharp to be the reflection of a bug that is so out of focus that you can't see it at all as a bug. Plus it's tragectory is far too straight. Also, there would be faint marks in the difference photo as wide as the percieved "wingspan" (the length of the white arc) all along the dark trail in the sky.
So here are some things that we can tell about it's position:
The "impact" must be in front of the lamp. You can see from the difference photo that the white arc is not obstructed by the lampost.
As for the streak:
Case 1: The source of the dark streak is far away above the clouds. The difference photo clearly shows the trail fade abruptly in the sky, indicating it comes through the clouds at the point that it disappears. This point is miles away and high in the sky.
Case 2: The source of the streak is in front of the clouds and in plain view. We obviously can't see anything in the sky generating this, so whatever it is must be invisible.
If the source is invisible, then we are dealing with either space aliens or top secret govt. technology, both of which I find pretty unlikely.
If the source is far away and above the clouds, then the trail would appear much smaller in the distance as it got further from the camera, which the difference photo shows it does not. It stays the same width for it's entire path. The only explanation for this is that the trail is a focused beam that happens to be at the perfect angle for the effect of distance to counteract the collimation of the beam. Even so, unless the focal point of the beam was at the camera lens, then the beam would not be a cone, but have a curved cross-section which would also indicate alien technology, since there are no known beams which collimate in anything except a cone. Also, if the beam were collimated, then the darkening effect that it is having on the atmosphere would get more intense as it gets smaller and closer to the lampost, which it clearly does not.
My only conclusion is that it is a fake, or evidence of aliens. I'm leaning towards fake since I don't see why aliens would be cruising our planet shootin' at lamposts with their nondestructive flare ray in their cloaked spaceship just for kicks.
More reasoning for this: The white arc is not perpendicular to the streak, indicating that it's point of origin does not lie on the line of the streak.
Lastly, over the course of 30 seconds that these three images span, why have neither of the ships on the water moved even a pixel? I think these photos were taken much closer to each other than the EXIF data suggests.
Just my thoughts.....
-Z
Here is a link to the difference photo again since this thread is now like 40 pages long....
http://images.isja.org/images/strange_diff_pryde_01.png