PS3-Sense writes: "There have been quite alot of contradicting rumors about the name for the sequel to Call of Duty: Modern Warfare. We thought it was time to find out what the name will be once and for all, which is the reason we approached Activision Blizzard Benelux. We got a definite answer from Martijn Kroonstuiver, PR Manager at Activision Blizzard Benelux.
"For now, we're using the name Modern Warfare 2 as it is a sequel to Call of Duty: Modern Warfare."
So unless Activision changes their mind again, the game will definitely be called Modern Warfare 2."