The SOCOM 4 Multiplayer Beta will roll out in four separate phases. It'll begin with a small, private group and then expand weekly from there until it's freely available to everyone! Here's the schedule for each of the beta's rollout phases:
* On March 15th, a private beta goes live. We’ll be contacting eligible players soon.
* Beginning March 22nd, PlayStation Plus members will gain access to the beta.
* On March 29th, anyone with a beta code included with Killzone 3 gains entry.
* Starting April 5th, the beta will be freely downloadable to anyone via PlayStation Network.
via socom.com