yobongo Location-based chat startup Yobongo is opening its iPhone app beyond its private test today — now any user in San Francisco, New York, and Austin can sign up.

The app was created by Caleb Elston and David Kasper, two former employees of livestreaming video company Justin.tv. When they first announced Yobongo back in January, Elston described it as “a place for authentic conversations with people who are physically nearby, whom you might not know yet.”

The interest in mobile chat continues to grow. Just this week, Facebook acquired chat app Beluga, while Ning launched its own mobile social service Mogwee. But these apps are really focused on connecting you with people you know. In Yobongo, you can chat with anyone, as long as they’re nearby.

Behind the scenes, Elston and Kasper have worked to make the app as simple as possible. When you sign up, you don’t have to look for a group to join — Yobongo just places you in the correct room based on your location. For now, Elston said the app will probably just have one room for each city, but it dynamically adjusts the rooms based on activity, so as the user base grows, we’ll probably see rooms based on specific neighborhoods.

But even without that narrowing of focus, Elston said that among early users (who are mostly in San Francisco) he’s already seen one group connect for the first time in the app, then meet up in-person for brunch.

Of course, like every mobile chat app, Yonbongo is hoping to see those interactions really take off at the South by Southwest Interactive conference in Austin later this month.