[UPDATE] According to Ryan Payton, Assistant Producer at Kojima Productions, the game is fake.

Original story:

With the release of Metal Gear Solid 4: Guns of the Patriots upon us, speculation surfaces this morning that Konami may be ready to unveil a new Metal Gear title for the PlayStation Portable (PSP) at this year’s E3.

The rumor comes from Russian site StarSniper, which was down at the time of this writing. However, a member on the PlayStation.com forums dropped some information about the supposed upcoming PSP title.

“The game is titled Metal Gear 3: Revolver Ocelot and it takes place between MGS: Portable Ops and Metal Gear 2: Solid Snake. It will feature some scenes from the original Metal Gear.”

“The game uses a recruitment system similar to MGS:PO and the main character is Revolver Ocelot, looking similar to both MGS3 and MGS1. Big Boss is not a playable character, but appears sometimes during the cut scenes supervising the construction of outer heaven.”