(Perhaps too much. Stop reading now if you would prefer to keep Black Ops' locations, plot points and still unannounced modes a secret. Josh Olin, community manager at developer Treyarch, implies that the "leaked" achievement list is authentic on Twitter.)
We already knew about Call of Duty: Black Ops' zombie mode, so that's not a surprise. But Dead Ops Arcade? That's listed separately from the zombie-based gameplay and pits players, at some point, against a Cosmic Silverback. Other achievements related to a location known as Rebirth Island might explain what that involves, since simian slaughter factors into the achievement "I Hate Monkeys."
While Call of Duty fans may already know about the game's international destinations, including Vietnam and Russia, it appears we'll also be visiting Hong Kong. Black Ops will also send players to a POW compound and the Pentagon.
It appears that only one achievement may be related to Call of Duty: Black Ops multiplayer. To unlock "Gamblin' Fool," players will have to take part in the game's new Wager Modes.
There are still a few secret achievements, potentially serious spoilers, that are listed as "Classified." If you're curious, and don't mind ruining major plot points, read all about it at Planet Call of Duty.