Tweet by @simonpegg last night:
Let the Sulu and Scotty slash fiction begin! http://twitpic.com/cpg1zo ...seriously, they _all_ know about fanfiction and slash fanfiction.
Had a discussion last night on lj regarding Bruce Greenwood and his Pike-Kirk statement "our love for one another is abundant"... I don't think he actively feeds us, but he must know about Pike fanfiction unless he lives under a rock - which he doesn't. Most of the cast members either already had fandom experiences (Quinto as Sylar in Heroes, Urban with Xena and LotR, BC with his own big fanbase) or must have known what they have to expect (Chris Pine as Kirk in the famous Kirk-Spock-relationship!).
As much as the fileshare quota of a movie signals how much people love it, having people write fanfiction for a character one played is a good sign. More fanbase -> more visibility -> studios having more interest into bringing you into new shows. There's a lot of strategy going into casting, and if you e.g. put Karl Urban into something, you already secured at least his own fanbase as watchers.
If you produce a movie or series today and it doesn't have a fandom at some point in time, you're doing it wrong.