His last post on the forum was an announcement of a new Bitcoin version release. It didnt really have the feel of a parting post; it is suspected that he left because Andresen was scheduled to speak with (feel free somebody to correct me if I'm wrong here but I believe it was) the CIA. That and the whole association with WikiLeaks got him paranoid that the government would soon be after his identity.
I just think its kind of amazing that he somehow knew bitcoin was not only going to succeed but be revolutionary. I doubt many people beside himself at the time had confidence that it would go on to have a multi-billion dollar market cap and be as transformative to finance as it currently is.
The timing of his disappearance from the public eye was more or less perfect, and its doubtful he will ever return. Why risk screwing up a good thing you got going?
Unfortunately, people are using bitcoin not because they like the technology but because it is making them money through it's volatility.
Sad to see that people are using bitcoin for not it was meant to be but just because it's making them money.