This may have been touched on before, but for those who believe Palpatine and Sidious are not the same person, there is one little clue that, if you're not looking for it, you might miss it. Look at how Sideous walks, particularly the position of his hands, when he is talking to Maul in Ep. I on Coruscant. Then look at Palpatine in the scene with Anakin in Ep. II. His hands are in EXACTLY the same position when he walks. I'm not sure if this was deliberate or not, but I thought it was the most obvious clue to the non-fan that they are the same person.