Treyarch and Activision will release Call of Duty: Black Ops 2 on November 13, 2012, but you can take a peek at what's to come right now thanks to a newly released and somewhat spoiler-y Xbox 360 Achievements list, from Xbox360Achievements.org. The big news is that, for the first time since Call of Duty 3, players will be able to up their gamerscore in the game's adversarial multiplayer mode.
Infinity Ward stepped away from multiplayer Achievements with the release of Call of Duty 4: Modern Warfare in 2007, which introduced an RPG-like system of unlocks for use online. Treyarch offered a couple in World At War with a 0 GS boost attached, but the developer followed IW's lead after that in the first Black Ops, with no adversial multiplayer cheevos.
In Black Ops 2, you'll be able to earn multiplayer Achievements for leveling up to 10, activating Prestige mode "in multiplayer Public Match," winning five games in League Play after being placed in a division, and winning 10 matches in the Party Games playlist. There's also a separate cheevo for winning 10 games in Combat Training. All told, the multiplayer Achievements (plus the Combat Training one) are worth 100 GS in all.
A large chunk of Black Ops 2 Achievements near the top of the list are devoted to various facets of the single player campaign. Many appear to be story-related, though a few others point to additional features. Arcade mode or some score-based equivalent seems to be back in Black Ops 2. It seems there are also mission-specific challenges to be completed, with a GS reward for completing all of them in a single mission. Yet another cheevo is unlocked for completing a level with a customized loadout.
On the Zombies side of the equation, fans can look forward to earning 200 GS worth of Achievements in the newly revealed TranZit mode (proper spelling for the Zombies campaign, apparently) and in something called "Green Run." The only revealing bit of info here relates to the mode's bus, which appears to be upgradeable in some fashion. The "Undead Man's Party Bus" cheevos is worth 15 GS for completing "all additions to the bus in one game."