It has been confirmed that Cate Blanchett has joined the cast of the two-part Hobbit movie. She will be reprising (preprising, as this a prequel?) the role of Galadriel from the Lord of the Rings movie trilogy.
In addition, Peter Jackson has confirmed that Sylvester McCoy (the seventh Doctor Who) will be playing Radagast the Brown. This redresses Radagast's absence from The Fellowship of the Ring, where he was in the book but not in the movie. Radagast isn't in The Hobbit (although he is mentioned) but is in the film. Other casting announcements are that celebrated British actor Ken Stott will be playing Balin (whose tomb Gimli freaks out over in The Fellowship of the Ring), whilst Swedish actor Mikael Persbrandt will be playing man-bear hybrid Beorn.