How do teams work on projects?

How do teams work on projects? Even with unity pro and .meta files for source control systems. Scene files are binary, so only one person can work with the main scene. How can teams work on a project without namespaces?

Unity seems to be too limited and oriented on indy developers.

Answered my own question with a big blog post at http://va.lent.in/blog/2011/12/13/so-how-do-teams-work-on-a-big-unity3d-project/

There are lots of tools to manage your team and communicate with them easily.
I found 14 free tools for team management.

There is a solution for teams who want to work on scenes together. Scene Fusion is like google docs for Unity. There is a free version available to get started with.