I work on a very similar team, about 25 people, distributed globally, all contributing to various Open Source projects, all with different processes, governance, etc. Our managers focus on handling the management and human resources bits, ensuring that I have what I need to do my job. Most everything else; time management, development process, tooling, location... even travel, etc - is left up to me.
I personally feel that the key to the team is the core belief that everyone's an adult, and can manage themselves and their own work. Managers aren't authoritarian, they're coaches. We're all encouraged to be strategically minded, though a lot of that is taught and socialized in the team's always-on IRC channel. The team was founded by adapting the Valve handbook, throwing out all the things that require people to be colocated. Other than that, the unique dynamic of autonomy, mutual respect, support, and the freedom to ask any question - no matter how dumb it may seem at the time - isn't something I've ever seen reproduced elsewhere.