Game Dream 5: Cooperative Storytelling

Doc’s Fifth Game Dream talks about Cooperative Storytelling:
To what level (if any) do the groups you usually play with encourage communal creation of the game world? Are the players spectators, or do they actually have a say in the plot (moreso that just guiding it by the actions of their characters)?

In campaigns, the plot can hit my characters over the head, characters can alter and change things as per their abilities, verve and wit, and in the case of proactive and fully engaged PCs, make their own plot.
Let me give you some examples:
Oliver, being a new PC to SB, has gotten into the game with a plotline hitting him over the head and making him a stranger in a very strange land. He’s still reacting and working through this. But even here, Michael has been very good about suggestions, intimations and such, instead of mechanically responding to what is happening.
Brieanne is at the ball, after the wreckage of the flow of the ball thanks to the Declaration of Rebman Independence. She has taken active measures, in its wake, to awaken and liven up the ball, not content for the GM or anyone else to do it for her. So, together, the next phase of the ball is working out thanks to PC action.
Jayson is making his own plot at this point. He has goals, plans, ideas and is putting them into motion. In fact, a side effect from a previous idea of his caused me to extend it into a game-arching metaplot because it was too good not to use. Being a long established PC, Jayson and his player are confident in making their own bliss in SB…and it does dovetail and play nicely with other Players and the Major Plot, rather than being an exercise in “Baldur’s Gate”
In one-shots at cons, plot is somewhat more rigid–but I am always amenable to things not following a certain script. The fact that I wound up with PvP combat in two of the games (and thus major change from envisioned events) is indication that I don’t force things down a particular track. The fact that JP Brannan’s character wanted to revolt against the PCs changed the plot of DMF severely–but it also made for a juicy and interesting experience.
I like it when players are confident enough with me and comfortable enough to not want to merely react to my turns in a mechanical manner.