The promo code for the SOCOM 4 beta that came with each copy of Killzone 3 will become active starting tomorrow at midnight. Users with the code will be able to access and download the beta from the PlayStation Store. The beta previously included selected players as well as PlayStation Plus members.
There are two playable maps in the battle, each with a myriad of different game-types to try, including SOCOM's variation of deathmatch, Suppression, then Last Defense, Uplink, Bomb Squad, and three custom game types: Sniper Alley, Last Defense Run n' Gun and Scrum.
Each game type, excluding custom ones, can be played in either Standard or Classic modes, with Classic being more along the lines of traditional SOCOM games with no regenerating health and no respawns.
SOCOM 4 hits stores on April 19 and will support the PlayStation Move as well, there's a pretty sweet bundle if you don't already own the motion control device.
Source: PlayStation Blog