No, It'll be open to everyone. I originally intended to limit this to SF but have changed my mind since.

I initially tested out this idea by creating a simple form that asks users for their name, email and zipcode and manually pairing them up myself via email. I limited that to San Francisco zipcodes only, since I figured it not doing so would mean that I would have a bunch of users who may not have anyone nearby to get paired with.

A lot of people who weren't in SF actually emailed me and expressed their disappointment in not being able to try it out. So this time I'm opening it up to everyone.

If you are the only one in your city, you'll get a message telling you so and you'll be paired whenever a new user in your city signs up.

If anyone has any better ideas, I'm open to suggestions regarding this.