There is a discussion on the development list about some clients wanting to "push" content from a staging server to the production server.
One way to do this for content is using John VanDyk's publish and subscribe.
Another is Node Import/Export which is being written by Jeremy Epstein as part of SoC.
Those can be taking further with users and roles too being migrated from staging to production, and that can be a truly federated environment.
You can see the original discussion in this thread.