SF30 has an interview with Guillermo Arriaga, whose recent work Babel is due to be released in cinemas approximately October for a limited release in the US and then national release in November.
There was mention of Diego - it's brief and only one, but the interview then moves on to speak about The Night Buffalo.
Relevant mention:
But long before he achieved an international rep as a screenwriter, Arriaga was a novelist, TV producer, and documentary maker. His 1999 novel "The Night Buffalo," about a cocky Mexico City youth's turmoil following a friend's suicide, has just been published in English in the U.S. (Arriaga produced the film adaptation, which stars Diego Luna and is in postproduction.) The tall, bearded writer made a local stop last month during his abbreviated book tour, and we spoke a few hours before he headed out to the Balboa to introduce a screening of "The Three Burials of Melquiades Estrada."