This has probably already been discussed but if not, then here you go. LINK 343 will be releasing the rest of the specializations within the coming weeks.
“official” source, here:
http://blogs.halowaypoint.com/Headlines/post/2013/01/09/The-Halo-Bulletin-1913.aspx
Thanks for letting us know!
Week of 1/21 Spartan Ops Episode 6: Five new missions and an accompanying new CG cinematic. “Forge Test” playlist (name not final): A rotational hopper featuring small Forge maps such as Relay. Help us test these maps by providing feedback and reporting bugs that will assist us in getting them ready for Matchmaking! Specializations: Pioneer and Pathfinder Specializations unlocked for all players.
Week of 1/28 Spartan Ops Episode 7: Five new missions and an accompanying new CG cinematic. Grifball playlist: A rotational hopper featuring everybody’s favorite virtual sport. Catch the disease! Specializations: Engineer and Stalker Specializations unlocked for all players.
Week of 2/4 Spartan Ops Episode 8: Five new missions and an accompanying new CG cinematic. Team Doubles playlist: A rotational hopper for those of you that like action of the 2 vs 2 variety. Specializations: Rogue and Tracker Specializations unlocked for all players.
The Majestic Map Pack arrives later on February 25, which is also around the time we’ll see a title update (details to come). IGN will have extensive Majestic coverage, including a ton of video content, in the coming weeks.