Lionhead has confirmed that the Fable 2 DLC "Knothole Island" will be available for download on January 13th. On the same day there will also be a free title update that adds some free items and lets those without the DLC play it via co-op mode.
Lionhead has also released a new video diary:
"In the latest installment of Lionhead Studio’s Video Diary series, the developers reveal some of the challenges they faced in the final days of making “Fable II” and offer a sneak preview of Knothole Island. Senior Programmer Jonathan Shaw and fellow members of the team hint at the new quests, weapons, items and specialty shops available on this mysterious isle off the coast of Albion, as well as some of the quirky characters that inhabit it."