I had really planned not to give any more airtime to Kojima Productions' infuriating countdown-to-a-countdown nonsense that's happening over on their official site, but then they went and added an element to the teaser site that's actually worth talking about. Curse you, Kojima!
Perhaps you will recognize this distinguished gentleman.
If there were any doubt at all that the forthcoming announcement is Metal Gear-related, you can put it to rest. Kotaku's Brian Ashcraft also went and dug up a forthcoming Famitsu interview with Kojima that has not only this picture of Big Boss but also a similar one of Raiden. Or could it be Gray Fox, as Ashcraft speculates? That would keep the timeline consistent, and it wouldn't be the first time Kojima pulled the whole "this old character looks identical to this younger character" switcheroo.
My cynical expectation out of all this mess is a God of War-style flashy action game starring MGS4-era Raiden. He's got the moves for it, and hey, those kinds of games sell! I hope it's something more original than that--and whatever it is, we'll know in less than a week. Commence your own speculation!