It has been confirmed by TV Guide that Cameron, Chase and Foreman will all be returning to "House" in season four. In what capacity, however, we do not know.
It seems that four new people have been added to the cast, all of whom are going to be the new set of ducklings: Olivia Wilde, Kal Penn, Peter Jacobson, and Anne Dudek.
So, the cast just went from six to ten. I'm really not sure how they're going to handle this.
EDIT:
You might have noticed that Wilsons-House (https://www.deviantart.com/wilsons-house) has been, well, dead for the last couple of months. Or maybe not.
Truthfully, our troubles are many here at this club, but chief among them are that your droogs are all