Thanks to Isis at Crowe's Crossing, a list of upcoming books on Braddock and the film:

Cinderella Man
by Marc Cerasini
Paperback: 304 pages
Publisher: HarperEntertainment (May 1, 2005)

Cinderella Man: The Shooting Script
by Akiva Goldsman
Paperback: 160 pages
Publisher: Newmarket Press (June 1, 2005)

Braddock: The Rise Of The Cinderella Man
by Jim Hague
Paperback
Publisher: Chamberlain Bros. (March 30, 2005)

Cinderella Man: James Braddock, Max Baer, and the Greatest Upset in Boxing History
by Jeremy Schaap
Hardcover: 288 pages
Publisher: Houghton Mifflin (May 3, 2005)