What kiba said. And don't underestimate the power of face-to-face meeting to build a sense of shared community.
Agreed with SunAvatar and kiba. But I prefer smaller meetings then a bit conference. Small meetups are always good -- better then one big, expensive, complex and centralized conference.
It is an interesting point. Small localised meet-ups but with some connectedness is harder to suppress if it comes to that. Brings to mind the operation of "terrorist cells" chillingly.