I can't believe a 757 hit the pentagon and didn't cause more damage than that. The simple fact that the amount of kinetic energy being carried by a plane of that mass traveling at that speed would cause an explosion 5 times the size it did, not to mention at the very least much more damage to the building, lawn and surrounding area.
Now, could a smaller plane have it it? Sure, that's certainly plausible, but a 757, I just can't logically believe that given the pictures and video released. Obviously something hit it, there was some debris of a plane and a brief glimpse of an object on the video, but there's just no way a 757 hit it.
Is it a conspiracy? I don't know nor do I care. I'd like to see another investigation done but I fear too much has already been shuffled away or "lost" to really give us any more information.