I am only three posts into reading this thread, but want to put in my initial two cents. I first heard about BBM back in October, by following one of my favorite posters at IMDb through his posting history, to some IMDb forum called "Brokeback Mountain." Weird name. I started reading his posts, then all posts. I had never heard of (I confess) Ang Lee. I had barely heard of (and discounted as shallow, too-young) Heath Ledger and Jake Gyllenhaal. Randy Quaid was really the only person in the cast or crew that I was familiar with. And Larry McMurtry had done Lonesome Dove, which I adored (and if you're looking to cast your BBM-oriented net wider, read, then watch Lonesome Dove. Not only is it excellent and about two long term cowboy buddies who go through a range of emotions between each other, but it's satisfyingly lengthy, no short story.) I had vaguely heard of Annie Proulx.
Just reading the IMDb board got me hooked, two months before the movie came out. I downloaded the short story, put it in my Palm, and wound up reading and rereading it continuously, every moment I could. Stayed awake late rereading, couldn't stop. Started posting. More soon.