It seems to me like Hollywood is glutting itself on contemporary teen fiction. Twilight is obvious, but there was also Paranoid Park and supposedly Looking for Alaska is in serious development, ditto The Book Thief and King Dork. I'm sure I'm overlooking others. My first thought was, "gee, this must be unprecedented!" but of course, that's wrong.
A little Googling unearthed some interesting articles, particularly this one from ALAN Review in 1994. Apparently, between 1982 and 1989, two Robert Cormier novels (I Am the Cheese and The Chocolate War) and three S.E. Hinton novels (Tex, Rumble Fish, and The Outsiders) were made into movies by major studios. I'm sure there were others then, too. So much for unprecedented.
In the context of comparing teen movies and teen books, the article offers up this pre-J.K. Rowling gem of an observation [italics mine]:
The teenage film market is different from the teenage book market. The book market is relatively splintered; so a single book will probably never connect with the entire market. And the market is smaller than the potential film market because publishers need readers, that is, youngsters who are literate. Filmmakers do not have that restriction since almost all people have been trained since birth to comprehend many, if not most, films.
Another market difference is that teenage books are cheaper to produce but are potentially less profitable than films. But books can make money, particularly if a book is accepted by English teachers. Whereas film marketing goes directly to the teenager via television, radio, and word-of-mouth, book marketing targets teachers as agents. The success of Hinton, Blume, and Zindel can at least partially be attributed to the free marketing provided by English and language arts teachers. The book market benefits from free reading assignments,book reports, sustained silent reading, whole language theory, and so on.
I find it particularly fascinating to read this a few hours before I go see John Green and co. on their Tour de Nerd Fighting (which feels like it's been creeping up on me for months since things tagged John Green have been dominating my Facebook feed). Things have changed, eh? Have teen-novels-to-teen-movies changed, too?
Seriously, though, it's a fascinating, if scholarly, article. It also leads to an article called "WHAT IS HOLLYWOOD SAYING ABOUT THE TEEN-AGE WORLD TODAY?" by famed critic Michiko Kakutani. The article is behind the pay wall (thought they'd done away with that), but I may spend the four bucks anyway.
I think there's a fair amount to be learned in examining what happens between book and movie (aside from the author quitting his day job and moving to Switzerland to hunt butterflies). More study will be required.