We'll find out for sure on May 31, 2012, but a quick look at the site's source code indicates that this is a "CLOS Teaser Page," leaving little room for imagination. The page source also offers a brief description: "Dare you face the evil darkness? It is written that the creatures behind that door will return very soon to claim the souls of your loved ones, and send you straight to hell! Be aware!"
I'd rather hear about the rumored 3DS game, myself. Even still, I'm always down for more Castlevania, no matter what form it takes.