Notice the (s) above? Yep, that means more than 1 release date for the beta! The Official Sony Playstation Blog announced today that the beta will begin in just a few weeks, but certain batches of people will begin to play up until it's up for everyone else.
Via the Playstation Blog, "The SOCOM 4 Multiplayer Beta will include each of the game’s competitive multiplayer modes — Suppression, Last Defense, Uplink and Bomb Squad — all playable on the maps “Port Authority” and “Assault & Battery”. And of course, you’ll be able to play each of our modes in either of their Standard or Classic variants."
I just realized this, but there sure are a crapton of betas being released