It just occured to me that the island having the ability to move now explains how the pirate ship in season 1 got landlocked in the middle of the island, as the island was probably elsewhere at the time, and when it moved back then, that ship happened to be at the location of where the island would move to.
Yup, alien spaceship, that's what the island is. Or maybe I'm too eagerly awaiting the next season of Stargate: Atlantis.
