In a news post today Ubisoft announced "The Tyranny of King Washington" DLC with details regarding prices and background.

"Greetings Assassins,

We are pleased to officially announce the Assassin's Creed III Season Pass!

The Season Pass will give you access to all five forthcoming DLC's which are slated for release within six months after launch. Assassin's Creed III downloadable content will feature an all-new single-player campaign available as a continual episodic story through three DLCs in which players will experience an alternate history of the American Revolution dubbed "The Tyranny of King Washington". As the revolution comes to a close in 1783, driven by the desire to ensure the safety of the colonies, the Revolution's greatest hero, George Washington succumbs to the temptation of the Apple of Eden and a new King is born.

In addition to this all-new single player experience, the Assassin's Creed III downloadable content will feature new maps and characters for an even more expansive multiplayer experience as well as other single-player missions.

Assassin's Creed III Season Pass will be available for purchase for 2400 Microsoft Points on Xbox LIVE or 23,99 on the PlayStationNetwork."