Signed message or this is just another PR stunt for whatever the reason this man may have.
I call BS and all future Satoshi-wannabes who are not able to sign a message or talk themselve around doing so.
a signed pgp message is one thing..
but something that would cause controversy is not the identity of satoshi. but if satoshi still has privkeys of addresses from january09-summer09
and annoncing that just 0.1btc will move from an early address on christmas day (pre-announcing it) and then actually doing it on the day.. well that would solve any speculation that the early funds are or are not lost to oblivion
See edited content above. I should just have posted it as a new post, but anyway. Edited it. Just my 2 cents.