What is Game Day 2013? That's what Sony wants you to ponder as you watch the above 16 seconds of... something. The clip was posted on the official PlayStation YouTube account yesterday with no supporting info. All we have to go on is a date at the end of the clip, February 1, 2013. Otherwise known as "this Friday."
The safe bet seems to be that this is a God of War-related announcement, based largely on the woman in the clip's Greek-ish dress and the ash that starts to swirl around her toward the end. Why the secrecy though? It's not like you don't know that God of War: Ascension is coming in March. And what does "Game Day 2013" mean? All will be revealed soon enough.