During one of our lean client engagements, we conducted half a dozen value stream mapping sessions with various groups and project teams from the client organization and this session was an interesting exercise. The session involved a large cross-functional team responsible for maintaining a very large-scale system and we wanted to get representatives involved from each stream / discipline (PM, BA, Dev, Test, Training, Architecture, Service Management, Infrastructure) to get the holistic picture. We ended up with a group of ~20 people and one of our facilitators (i.e. Jeff Anderson) decided to facilitate using a decentralized approach and handed out stickies to everyone and asked everyone to come to the wall and map out their specific processes in the value stream. This is what we ended up with:
Needless to say, I am having a "fun" time transcribing this into a visio diagram (we promised the client we would capture the value stream and give it back to them as a deliverable). Next time we have such a large group, I think I will use a different approach (lesson learned).