Noisebridge is run by consensus with all the members. We don't do anything as a group that everyone isn't OK with (not everyone has to be wildly enthusiastic). We've evolved a way of getting to this state, which is not any kind of definitive rule, but has worked reasonably well so far. Here's what to expect in most cases, except when we get to consensus by a different method.
Usually there is discussion about a topic between members in person, on the mailing list, and/or on IRC. At some point someone puts the topic on a meeting agenda so it gets discussed on a Tuesday night. If we seem to be in sufficient agreement, someone will put the item on the next meeting's agenda as a consensus decision item. Generally we try to have at least one week between the first meeting discussion of something and the actual decision, in case there are members who haven't heard about it.
The process is decision-centric, and should be able to re-configure itself around the decision that needs to be made.