Saw this last night , wanted to see it immediately again afterwards.
Thought a bit about the whole "Space jockey not being in the seat in the ship" thing . I thought that the planet that the derelict spaceship was on was Lv426 ? So my theory is that there are still jockey's ( or Engineer's ) on the ship that Shaw and David flew away and that this ship is in fact the one we see at the beginning of ALIEN .
I could see one of the Engineer's taking over the ship after Shaw dies ( who has been hatching another embryo in her chest from some "oil" that was on the ring she put onto her finger after her caesarian ) and trying to pilot the ship but the Engineer has became infected with Shaw's "offspring" and that is what burst out of his chest ?
Boy I need to get out more often !