You should never underestimate the value of face-to-face communication, especially with large and distributed teams. You should do everything you can to provide as many opportunities as possible for direct communication. Direct communication, together with transparency, helps to build trust, both inside the team and between the team and the outside world. If team members trust one another, they will not fear taking up responsibility.
A tool like the wiki Web will help you build trust by empowering everybody through shared ownership. In doing so, such tools change the flow of communication from control-driven to collaborative-driven.
When building subteams, you should ensure that the skills within each subteam are mixed. Furthermore, the technical service teams should serve the domain teams. If so desired, they can also be established as virtual teams.
Last but not least, allow the team to have fun. This not only helps teams jell, but more importantly, it also makes the work environment a pleasant one, which will make everybody want to work and succeed with the team. Consider the values of the gift economy the way the open source does; this will also help make work much more enjoyable.