MP1st - Modern Warfare 3 Premium Elite users on the PS3 can now download the three new Elite drops. Drops 4, 5, and 6 include one multiplayer map, Black Box, and two spec ops missions, Negotiator and Black Ice.
Update #1: Sledgehammer Games' Michael Condrey has confirmed that non-paid Elite PS3 owners will be getting the first content collection on April 19th as MP1st speculated. He stated, "Its raining MW3 DLC! Drops to both Xbox 360 & PS3 Elite this week, Collection 1 to the PS3 on 4/19."
Update #2: Infinity Ward, via Twitter, assured PS3 owners that Colletion 1 will be available on April 19, but there's still no confirmation on when it will be released for PC. The studio explained, "Collection 1 hitting all PS3 next Thursday, April 19. PC coming soon"