There will be a B&N exclusive edition of Nightfall, with the bonus of illustrations and a short story from Keefe's pov.

"This limited collector's edition of Nightfall contains beautifully illustrated endpapers drawn personally by the author, as well as an exclusive story from Keefe's point of view that will reveal some of Keefe's deepest thoughts—including about Sophie!—to readers."

source: B&N website

Feel free to share any other Nightfall confirmed tidbits.