"You can slice enemy's throat with knife if you flick the touch pad behind," he said, referring to the throat-slitting maneuver in Metal Gear Solid 3. The "touch pad behind" is of course the Vita's rear touch pad. You can also move left and right on the rear touch pad to stretch in first-person view. Of course, these aren't just a neat bonus -- as MGS2 and 3 used all of the PS2's control options, including analog buttons and the L3/R3 buttons, some changes had to be made in the transition.
Kojima shared a couple of photos of MGS3's title screen and HD Collection menu screen on Vita, taken while sitting in a recording studio. Why was Hideo Kojima in a recording studio? Because actor Ginga Banjou was recording new lines for the game -- as Major Zero explaining the Vita controls.