IIRC, Satoshi never used the same IP address twice.
I think I may know who ... at least, I know someone who could have written the code (in terms of expertise) and had a good reason to, and who would have, for very good reasons having nothing to do with Bitcoin, disappeared from active development at about the same time as Satoshi did, and who has enough money that he wouldn't need to spend all those coins that Satoshi mined just the same way Satoshi hasn't.
But, y'know, that isn't proof.
It's all circumstantial. And I won't name names, because I respect the guy (whether he is or isn't who I think) and he didn't want his name known.
And besides, even if I'm right, nobody's really gonna know until his will is read, and that's more or less as it should be.