This according to a recent report from the LA Times online blog:
"People close to the matter said Infinity Ward is working closely with Sledgehammer, which is led by a team recruited away from Activision's rival Electronic Arts Inc. The two studios are equally sharing duties of producing the single-player portion of the game, the sources said."
"Activision has also brought in Wisconsin-based Raven Software, which is working on the online multi-player elements for Modern Warfare 3, sources said."
Apparently Activision is concerned about the title after the heads of Infinity Ward, the game development studio that created the hit Call of Duty series, were fired last March, with most of their top talent leaving soon after.
Incorporating more than one game studio in the development of games may be a new trend for Activision as they have done it with other titles in the past. Last year's Medal of Honor, a reboot of the popular franchise, Danger Close was responsible for the single-player/campaign portion while the multiplayer was handed off to DICE, the same team behind the very popular Battlefield franchise.
The report also stated that Modern Warfare 3 is well into development and that it will be released this November, the same month that Activision has annually released the recent Call of Duty installments.
Apparently the recruiting of the Sledgehammer team to help out on Modern Warfare 3 is forcing Activision to delay production on a new Call of Duty spin-off game, which they began working on before the Infinity Ward upheaval, creating a domino effect for the franchise.
Modern Warfare 3 will be the first game Infinity Ward has produced since the departure of of company co-founders Jason West and Vince Zampella.