There is a lot of evidence that Satoshi went through great lengths to hide his identity from day zero.  The email address (throw away) on the white paper and p2p2 foundation have never been used (or at least found to be used) for anything else either before or after the release of the paper.  He used TOR likely from the very first day.  As Gavin pointed out he never talked about himself.  The same is true if you look at this posting history going back to the first announcement.  Nothing that would time his online identity to any physical location.  Nothing about local events, the weather, his past work, his experiences.   If he is from the west coast of the US, he delayed posting to newsgroups and forums to give the indication he was in another time zone.  If he is an American he chose a London newspaper headline rather than numerous US ones to choose from.

Pretty much everything points to a purpose driven man and the purpose was to remain private.  While it may be possible he did all that and still released the paper with his own name it would seem to be completely out of character.