This question arises from a G+ thread I participated in about the dynamics of certain gaming groups, but the question then became (to me at least) "How do you find a gaming group?"
The way I see it, a successful gaming group has a sort of "social contract". There are similar expectations in game style and system used. More importantly, whether playing via a virtual table top or face to face, the ideal situation should be that this is a group you would want to socialize with outside the limited parameters of gaming.
When I was a teen, finding a group was as simple as getting a handful of like minded friends or classmates together and simply playing. There was already a social connection amongst the players, and the natural teenage weeding out process brought the group down to a manageable core of close friends - friends I am still close to today, even if the gaming has moved to the latest MMO for most.
Finding a group as an adult is much more difficult. G+ certainly made it easier, and Greg's gathering of folks for a D&D Next playtest brought together a group of 8. Which dropped to 7, then 6. Moving to ACKS with me as DM put us at 5, so we added 1 to get to 6. Since then, we've added 2 and lost 1, so we've hit 7 (4 left from the original group). It's almost been organic in nature, and we've been pretty good at inviting those into the group that we felt would mesh pretty well. There isn't a person in the group that I wouldn't enjoy grabbing a beer with and just shooting the shit. I consider myself blessed.
So, how did you find your current gaming group?