While it isn't entirely clear about the whole process, it is known that when you post 50 messages you will become a Regular Contributor after this we will soon find out the next step. Keep in mind, this service is only a few months in, but so far everyone seems to enjoy it as well as benefit from all the great info !
We know that by the end of the month LL will select a few of the Contributors to move up to "VIP Contributor". This will be the highest rank that we know of so far. But LL also promised a reorganization of the Community Board and site early next year. Perhaps, there will be some more detailed explanations how the hierarchy of ranks is set up. In the meantime, we are having fun, sharing our experiences, asking questions and giving advise. I find some of the insight I gained and information I got about certain properties, I want to visit in the near future quite helpful.