A surprise to absolutely no one, the LinkedIn profile for a senior animator at Treyarch lists Call of Duty 7 as currently in production.
With Activision currently focusing on the next Call of Duty: Modern Warfare game from developer Infinity Ward, we aren't expecting any sort of official announcement on the next Treyarch version of the game any time soon. Still, it's pretty much a no-brainer, especially considering the success Call of Duty: World at War and its downloadable content have seen. A LinkedIn profile for Treyarch Senior Animator David Kim indicates that Call of Duty 7 is indeed in the works. He lists the game twice in his profile, once under his summary and again under experience.
Again, not really a surprise. We've reached out to Activision for confirmation of the listing, but aren't expecting much more than a no comment.