As long as the NSA does not reveal who Satoshi really is I do not belive that they have identified him yet. Satoshi was acting very careful what you can see in his action to stop being active after Gavin Andresen wrote him he will meat up with the NSA. Satoshi is genius and I doubt he would have made a mistake so that he is identifiable.
I do think it would be possible to ID people from the way they write. But I think also other people could find some very unique things that Satoshi said, and use google to find if there is another persona who wrote in the same way. Just the NSA has more data than google