This post should be tagged with "now how did I miss that?" Back in October of last year, Forces of Geek published a two-part article on Something Wicked This Way Comes. It's a well constructed piece of work, with a fine level of detail on the production history of Something Wicked as both novel and film.
The book started out as a short story - "The Black Ferris" - and later became (in this order) a film treatment, a novel, a screenplay, and a stage play. Quite a journey.
What is particularly good about the Forces of Geek article is that it includes a short comparison of novel and screenplay. Read all about it here.