One of Joystiq's bloggers was in a chat with a Sony executive. When talking about upcoming games on PSP, the exec accidentally slipped the name God of War. He was questioned further, "Wait, is this a confirmation?"
The Sony exec was obviously confused. "Yes. It's already confirmed. There was that instruction manual incident."
When asked further if the game was officially confirmed, he stated "yes" with further justification. While Sony hasn't officially unveiled the title to media outlets, it's pretty clear that it's coming ... and it's no hoax.