@Django
We had already craeted an MVP in the form of a community called Corporate Chat India that we ran for 1 year before starting GV. That experience taught us two things: 1) The operational side of running a community 2) That bringing similar groups of people together to talk has value (I know it sounds obvious but it has to be experienced to believe)
Perhaps, the above helped us make tens of good design choices when designing the first version of GV. Because our community had PMF, in theory GV would also have PMF (we just didn't know at what scale).
All we needed now was to solve the cold start problem.
Twitter really helped us here. We were able to get 5-8K really good people from Twitter within 3 days that kickstarted the GV product and the wheels have been rolling since.
happy to answer any more specific questions as well.