The official PlayStation Facebook page is teasing a reveal scheduled for April 19. The page (first discovered by VG247) lists the date and reads only: “Will vengeance brings redemption?"
Sony is staying mum on what exactly is planned, but I would guess God of War IV. The question posed matches the aesthetic of that series and while I wouldn't normally expect a reveal of this calibur to occur on Facebook, it should be noted that Geoff Keighley (host of GameTrailers TV and author of those wonderful Final Hours stories) retweeted a link to the page in question last night.
April 19 is a Thursday. GameTrailers TV airs on Thursday nights. They quite like game reveals on that show.
Take that speculation as you will.