As with the previous Call of Duty titles, the upcoming Black Ops 2 will be sold on Steam. Proof of this assertion can be seen in the screenshot below:
Given Activision and the game developer Treyarch's penchant for using Steamworks in both Black Ops and Modern Warfare 3, Black Ops 2 can be expected to follow suit with Steam functionality.
Despite the fact that Activision has yet to come out and confirm its use of the full Steamworks suite, it's pretty much a foregone conclusion. Steam functionality usually entails full support for Steam's friend list, invite/join functions, player matchmaking, player-hosted servers, voice chat, and groups.
Call of Duty: Black Ops 2 is set in the near future, taking place in what the game calls the "21st Century Cold War", where technology and weapons have converged to create a new generation of warfare. It is set for release on the PC, Xbox 360 and PlayStation 3 in November 13.