NEWS: Hideo Kojima is teasing the megaton in Metal Gear Solid Peace Walker

Hideo Kojima says of the new PSP entry in this week's Famitsu, "There's an unannounced system that will surprise you. It will make you want to rush out and buy a PSP."

Taking clues from his latest quotes might lead to an answer to what he is hinting at. At TGS he talked about a future where players would be able to "play a variety of games by simply connecting a computer to a network. If this were to happen, you could take your games with you wherever you went."  More recently Kojima said of Obama's Nobel Peace Prize win, "President Obama, who declared 'A World Without Nuclear Weapons' in Prague, has won the Nobel Peace Prize. Has the era at last started shifting? The start of the Peace Walker plan? I hope that comes to be. 'Peace will not walk to you.' 'You must both walk towards one another.'"

Hopefully he will drop more clues soon as to what this system actually is.
(source: IGN - read it!)