A long time ago I did a quick survey of Satoshi's posts just for fun and found that he seemed to be posting with a US time zone.
Here is the graph (X axis are hours, Y axis is posts, times are GMT):
And the data itself:
As you can see the night dip is between 6-11am GMT, so assuming this person sleeps at night, he should live in GMT-5 to GMT-7 somewhere which is the Americas.
Anyway, this was just a quick fun thing I did way back when. The reason I'm posting it now is that somebody dug up my IRC logs where I promised that I'd post it on the forums.