Here is a list of people you should follow on Twitter for all your Call of Duty news and details. These people give you info about their respective Call of Duty game and community.

For Activision:
Official Call of Duty account (@CallOfDuty)
Official Call of Duty: ELITE (@CallOfDutyElite)
Dan Amrich, (OneOfSwords) Activision Social Media Rep

For Call of Duty Modern Warfare 3:

Infinity Ward Studio:
Infinity Ward, (@InfinityWard) Studio for Call of Duty: MW3 
Robert Bowling, (@fourzerotwo) Creative Strategist at Infinity Ward

Sledgehammer Games:
Sledgehammer Games, (@SHGames) Co-Development Studio for Call of Duty: MW3
Michael Condrey, (@MichaelCondrey) Co-founder of Sledgehammer  Games 
Glen Schofield (@GlenSchofield) GM, VIP, & Co-founder of Sledgehammer Games
Guy Beahm, (@GuyBeahm)  Community Manager for Sledgehammer Games
Dave Blizard, (@blizzzz) CG Supervisor for Sledgehammer games

Call of Duty Community  V.I.P.’s:
Luckkyd, (@Luckkyd)
Mat Houchens, (@NuckFuggets)
Michelle, (@Medeiros83)
Dan Seamans, (@carbonfibah)
Ross, (@CODBlackice)
Morgan J East, (@MorganJEast)
Josh Torres, (@II_F0XH0UND_II)
Ryan Banks, (@PrestigeIsKey)

Unofficial Call of  Duty info:
CharlieINTEL, (@charlieINTELcom) Call of Duty blog.
MW3 Updates/Info, (@UpToDateMW3)
MW3 Modern Warfare 3, (@MW3Game)
Digital Warfare 24/7 (@DW247)


For Call of Duty  Black Ops:

Treyarch Studio:
Treyarch Studios, (@Treyarch) Studio for Call of Duty: Black Ops
Josh Olin, (@JD_2020) Community Manager for Treyarch
Josh Olin  Personal Account, (@JoshOlin)
David Vonderhaar, (@DavidVonderhaar) Game Designer for Treyarch Dan 
Bunting, (@danskdansk) Online Director for Treyarch
Treyarch PC Development, (@pcdev) Treyarch’s community PC  twitter account