Metal Gear Solid: Ground Zeroes will feature a 'MGS1 Deja-Vu' mission, exclusive to the PS3 and PS4.
While Metal Gear Solid is no longer the PlayStation exclusive it was in times past (except for those PC versions everyone forgets about...) it looks like the latest installment (or at least, the first part of the latest installment): Metal Gear Solid: Ground Zeroes will still retain some PS3/4 exclusive content. Series creator Hideo Kojima has confirmed that the game will feature a 'MGS1 Deja-Vu' mission, exclusive to its PlayStation versions.
As players play through the mission, they can enable a flashback system, which reproduces the 'vintage' visual style of the original Metal Gear Solid in all its triangle-polygon glory.
Metal Gear Solid IV: Guns of the Patriots featured a similar flashback moment, which allowed players to play through the beginning of MGS as a dream sequence.
A nice little touch for long-time fans of the series, but a pity that its exclusive to Sony's machines.