Well the "Big" announcement is finally here, and really, it's not all that big. Lionhead has announced a premium DLC pack called Knothole Island that unlocks new quests, armor, weapons and areas to explore and gain. The download is set to come out December 12th for a price of 800 MS Points, which seems to be the standard run of the mill pricing for DLC these days.
From what I gather if someone purchases the DLC, you won't be able to play the content co-op unless you purchase it yourself. In fact, if they purchase it and you don't download the free "co-op enhancement pack" you won't be able to play with them AT ALL.
Umm...really? Maybe I'm misunderstanding something here, but why wouldn't this just be included in a title update? Speaking of which - where's the update to fix some of the outstanding bugs Lionhead?
Source: Community.lionhead.com