Richard Barsam has written a very fine text for explaining the process of film criticism (Looking at Movies). One of the interesting points he makes early in the text concerns narrative theory. He posits the idea that we should have (for a ninety-minute film) the foundation of the film's exposition out of the way in the first ten minutes. It's a unique idea that speaks to the notion of showing versus telling. And it's a pretty interesting idea to apply to the process of writing, as art in each medium is classified as a "text."
Clearly, this rule depends on the genre in which you work. I read about a dozen mainstream "literary" novels each year, and I'm interested in how the storytelling differs from what you'll find in a lot of genre work. There's a much slower expository build-up in the literary writing. In terms of speculative fiction (and I understand I'm making a broad generalization), we often find the action early and prior to the exposition. I think the recipe indicates that you hook the reader (especially in horror fiction) with an "unspeakable act" and then trace back to develop the setting, characterization and back story.
So I'm interested. What do you think of Barsam's "ten-minute" rule? Does it hold for much of the stuff you look at? What about exposition in your writing--story first or detail first?