I've blogged previously about characters from TV shows (most notably Battlestar Galactica) showing up on Twitter. And it's not just BSG: just recently I started watching AMC's Mad Men, twittered about it, and shortly thereafter got a notification that "Peggy Olson is now following you on Twitter." It turns out that the twittering Mad Men characters are the work of fans, not the network, and that after a clumsy attempt on AMC's part to shut down the unauthorized tweets, the network relented and the characters returned to Twitter.
Having fictional characters turn up on the web is an interesting sideline, but the main stories on BSG and Mad Men are still being told on the shows themselves. But I've also been seeing more and more instances of people using Web 2.0ish ways to tell stories interactively. There was the War of the Worlds reenactment on Twitter last November (postmortem here, tweet archive here), itself a reference to Orson Welles' transposition of H. G. Wells' novel to the new medium of the radio and the resulting confusion between fiction and reality. And one of my favorite things on the web last year was an online series called Shadow Unit, a kind of virtual science-fiction/horror/police procedural about FBI agents, written by a very smart crew of writers and conceived as a written homage to episodic TV. It took me a while to realize that in addition to the episodes themselves, several of the characters were keeping LiveJournals in which the storylines continued to play out—and fans could interact directly with characters. It's as if Mulder and Scully had blogs where we all could comment, only somehow much more satisfying (probably because the Shadow Unit writers don't have to answer to any non-fictional network). I'm waiting eagerly for the start of the second season.
I have a theory that fiction and fan fiction are heading toward some sort of convergence with the social web, and we'll be seeing a lot more virtual audience participation (and creation, as well as participation) in the future. I suspect that Cory Doctorow's vision of a near future where masses of people contribute to an online novel, the best bits of which find their way into fan-produced physical books, isn't all that far from happening. I'll be very interested to see what happens next.