dockbit looks pretty interesting. The one thing that is always unclear about services like yours is how well it scales to hundreds of servers and how it integrates with other orchestration mechanisms/tools like fabric, salt, awscli, and other custom services and tools. I'd be interested in knowing more about how you're approaching that aspect since most places re-invent the same things over and over again internally.

The other issue is that what happens when you have downtime? Is my deploy train stopped because of it? How do I design things so that even though I use your service I still have fallback mechanisms?