Such books have been produced about other movies Ang Lee has done...why not Brokeback Mountain??
Today I finished reading
The Sense and Sensibility Screenplay and Diaries, by Emma Thompson. This is another in the series of film books published by Newmarket Press, and contains 50 illustrations including 36 color plates and the full screenplay as well as a long introduction by the producer. I was somewhat disappointed with the diaries although they gave a good peek into the daily life of a film shoot. Interesting, the early parts where the script was discussed and the beginning ceremony by Ang to bless the film. He also did quite bit of work with the cast to help them develop their characters and gave written homework.
After the script is finally written and agreed on, it's broken down into scenes which are completely rearranged to be economical and bundle an expensive actor's scenes all together into one session. It seems so scary and if I were working on such a project, I would wonder how it would ever come together again. No wonder that people work on a movie and then don't know if it's any good until after the whole thing is over!