Mustafa Isik has produced a system where two people can edit the same file in a chat like way. Conflict are resolved in real time. This, Real-Time Shared Editing, allows people to work together over the network, this could be a really good technology for when teams work from different sites on the same project. Technologies like these might allow teams to be worldwide, making the most of talent globally on the same software.
Google techtalks also has a presentation that gives an idea of how the system was built including a demonstration. The mechanism it covers for handling conflicts on the wire is explained: the techniques of Optimistic Concurrency Control may be useful for other styles of group working/conflict reduction.