For those who would rather be kept in the dark about Norris's involvement in the larger scope of things, we'll keep things vague. She shows up in the fourth installment (Dead to the World) of Charlaine Harris's The Southern Vampire Mysteries, the source material for the show. If you haven't read the books and really want to remain completely spoiler free, I would recommend keeping away from The Hollywood Reporter's casting reports for True Blood.
However likely certain upcoming additions to the show may be (i.e. POSSIBLE SPOILER: werewolves this season...END POSSIBLE SPOILER), some people prefer not to know, and THR gives away these sorts of things in their headlines. Just a heads up.
(via The Hollywood Reporter)