Thinking about not only the fact that we need a space, but what that space sense was in concrete terms, it strikes me that rich and vibrant online RPG communities like the one that formed on G+ (or historically, places like The Forge) have two qualities:
1. A shared and common space where a diversity of voices can be heard. That is, a shared timeline or a forum for people to speak into, where what you can see and who can see what you say is not silo-ed by who you follow and who or how many follow you.
2. Are driven primarily by conversation between and with designers, focused on facilitating the creative excitement, cross-pollination, and sense of possibility (see point 1) which motivates people in the community to become designers themselves and make new games.
I believe that these two are some of the major contributing factors to creating a rich creative environment for new forms of play to develop, and it is new forms of play which expand and enrich the community.
So I'm really excited about this forum!