Google Plus does already have an Events feature that carries the names of people going to a particular event and it just takes someone to post it as a topic in the main thread. Opensim Virtual has been running as a Google Plus community for some months and has seen considerable growth and interest from Opnsm grids and users.
When I started it I allowed anyone with a grid or interest in the open Metaverse to post topics about their grids, Metaverse news and virtual products. Since then quite a few grids and interested parties have launched their own G+ community groups too but, in general, most have remained small since they are promoting a particular grid. Opensim Virtual has grown to over 300 members and has proved very active with members taking advantage of the commenting options to express views on the topic in hand. Although G+ is not a search engine it does act rather like a bulletin board and has demonstrated that the open Metaverse does, indeed, have a fairly active community across many grids.
Opensim Virtual can be viewed here...
https://plus.google.com/commun...