Access the Metal Gear Solid HD Edition official site, and you'll see a mysterious message.
The text says "Spring Comes to Kojima Productions. The song in the background is Haru ga Kita (Spring Has Come).
What could it mean? The text above the message window says "11/07," so it's possible we'll find out then.
Kojima Productions has a particularly busy month ahead of it, with Metal Gear Solid HD Edition and Metal Gear Solid Peace Walker HD Edition due out (in Japan, these are being released individually).