CiviCRM has a core team of developers, a few of whom founded the project, who run the project and do software development as full-time employees. Donald Lobo and Dave Greenberg are the main "captains" of the core team, and when asked, they agreed that Lobo is the benevolent dictator when tough decisions need to have a tie-breaker.
The decision-making process is constant, but not transparent. As Lisa noted in her blog post, there is no clear place in the forums, on the website, the wiki, or elsewhere that the decision-making process is outlined.
This is because decisions often get made in conversations -- sometimes documented, sometimes not -- between people on the fly.
When asked, Lobo agreed that this is typically how something gets pushed forward in the Civi world:
It seems like a lot of decision-making emerges as prompted by energetic community members, like the following:
Joe Schmoe Community Member: Hey, I really think CiviCRM needs X bug fixed/Y functionality/Z documentation.
Lobo/Greenberg: That's a great idea. Can you submit a patch/start up a chat with W on IRC about it/write some documentation to get the ball rolling?
Lobo agreed with an assertion that the most energetic people closest in usually hold a lot of sway in determining how things go as long as they have the persistence and/or skills and/or funding to do what they're asking for.
This does seem to work in that it rewards the folks who are persistent and who have lasted long enough to understand the complex structure of the Civi core team and community.
However, what doesn't work is that anyone who expects clarity in this process, or expects to be able to follow a predictable set of guidelines in order to move something forward will be left behind.
My task this semester is to make progress on this front: I'm developing an FAQ to illuminate some important questions like this. It will be key to place this FAQ in as visible place on the website as the Civi folks will let me to intercept the confused folks who are new to the community with some answers. I'm also working on a piece that describes all the component pieces of Civiland as a guide so that folks at least can see a map of the different places the community exists and hopefully find it easier to decide where to plug in.