So here's my thoughts and philosophy on project liftoff, gleaned and garnered from more professional peeps than I:
Project life is inextricably linked to attention, thus exposure.
Exposure leads to attention, and attention brings participation, active or otherwise, to a cause.
Active participation is intentional promotion, development, artistic contribution, money.
Passive participation includes random mentions in conversation, intentional motivation to 'get it done' from friends and acquaintances, and other indirect positives.
Ex. You are working on a project that is near and dear to you, you talk about it to friends. Some friends jump on it like a mouse on cheese, and work diligently (more or less) on getting the project done. Other friends hear about it though word of mouth and contact you to help out. Other folks don't really have the expertise or time, but when the occasion comes up in conversation they rep your project, which may just happen to reach the ears of other such people who'd like to get involved.
Attention becomes more effective by how close the attendee is to critical project resources.
Critical project resources include things gained from participation that accelerate the pace of development and reaching successful product launch, and subsequently reaching a 'critical mass', a stage that once reached makes a project self-sustaining to a certain degree.
The next inextricable link is to developmental momentum. Attention from the core project participants brings momentum in the form of positive, directed discussion about the fundamental, core components of the project. This needs to be balanced with promotion. As the project goes along, certain points in the project lend themselves to being shown to the world to boost exposure. This also provides the all important ambrosia to the developer: motivation by adulation.
Ex. You get to a point in the project where 'cool things are happening'. Now is a good time to nurse your sleep schedule a bit and get some well needed motivation. You post up some pictures and maybe a video, and you get some thumbs up! Kudos, now more people want to see this thing live, and you can store up that motivation for when your eye sockets stop receding and you regain control of your hand movements and beat the shakes.
More brain dumpage to come!