MIT prof Henry Jenkins is pretty much the sharpest person I've ever met when it comes to the cultural implications of fandom, fannish activity, fan fiction, and participatory culture (a phrase he coined). He's started a blog, and just from the first handful of entries I know I'm going to be finding gems there every day.
First, the Snakes on a Plane phenomenon has been building momentum for well over a year now. In the old days, the public would never have known about a film this far out of the gate. They might have learned about it when the previews hit the theatre — a phenomenon which itself is occurring earlier and earlier in the production cycle — or even given the fairly low-brow aspirations of this particular title — when the film actually hit the theatre. In the old days, this would have been an exploitation movie of the kind that Roger Corman used to crank out in the 1950s and 1960s and destined to play on the second bill at the local drive-in. The goal would be to use a easily exploitable concept, a vivid poster and advertising campaign to generate heat quickly: then get into town and out again before anyone knew what hit them.
But, these days, grassroots intermediaries such as Ain't It Cool News are feeding the public's interest for inside information, starting to generate buzz almost from the moment rights are purchased or stars cast for a forthcoming production. Much as day traders have used the online world to become much more aware of every tick and twitch of the Fortune 500, the movie fans are ever attentive to anything which might impact a film's performance at the box office.