A question came up at my last Pathfinder game: If a character has Greater Grapple, does it become possible to grapple and pin an opponent in one round? ( not tie up, though. That'd be 3 checks. )
Once you have grappled a creature, maintaining the grapple is a move action. This feat allows you to make two grapple checks each round (to move, harm, or pin your opponent), but you are not required to make two checks.
Once you are grappling an opponent, a successful check allows you to continue grappling the foe, and also allows you to perform one of the following actions (as part of the standard action spent to maintain the grapple).
This leads me to believe that as long as the character has both a standard and move action, he can use one to initiate the grapple, and ( assuming success ), use the other to maintain the grapple and take his additional grappling action.