Content change process with multiple users

We are in the process of implementing EP 6.0, and plan to have multiple users that will administer the portal content. We are used to working in R/3 where there is a very structured change control process through transports, but there doesn't seem to be the same level of change control on the portal content side. We are concerned about administrators overwriting each others work in the development system, and I'm curious if any of you have a process in place that prevents this? Also, do any of you have a process to export/import developed content up to your Q/A and production systems? Is this simply controlled by one person?

Thanks,

Chris