I've found the best way to uncover the film shooter scene in SF is to carry a film camera around. Over the past month I've had a few people approach me to ask about it (my Canonet RF or Pentax 6x7) and I've approached a few.

I just came back from shooting at the Carnaval parade in the mission district, where I met up with a large group of 35mm RF/SLR folks I know. I was there with my Crown Graphic 4x5 and Canonet. I talked to at least another half dozen film shooters out there on Bryant St, mostly TLR users! I also talked briefly with a group of school kids who were all shooting film.