More content exclusively for Pro users is in the pipeline. In the post, Zipper confirms that “exclusive” multiplayer maps, “various” co-op add-ons, and dedicated leaderboards will be part of the deal, too.

The Pro pass is, in some respects, similar to Electronic Arts' vouchers. Using Mass Effect 2's Cerberus Network, the pass granted users access to some free DLC and other content. In Battlefield: Bad Company 2, the pass gave players "VIP" access, which translated to exclusive maps and guns. Zipper appears to be taking a similar route: no matter what, owners can play multiplayer, but without a pass, users won’t be privy to some game types, weapons and other features (i.e. "pro" custom game queues).
Of course, if you find yourself without a pass after the game releases (i.e. you picked up a used copy of the game), you’ll be able to buy one from PSN starting on April 26. The price? $14.99.
SOCOM 4 launches this week for PlayStation 3.