The back end of the craft has the notches for tugboats to push it around, so it's an unpowered barge. Also, although it's on an image boundary, that really is the correct front of the barge. I agree about the shape of it; the front looks a little out of place.
One thing that's not as visible in this image as in other images of this barge is the tower placed on the image boundary, which seems to separate that boat-like front from the rest of it. You can see the shadow of the tower as the square shadow though.
Given that this is also visible in the Virtual Earth images in this same spot, I am betting it's there as a navigation aid. It seems like that tower might be large enough for there to be someone up in it to watch the boat traffic, but it's probably more highly likely to be some sort of a large beacon. Those would be my guesses anyway.