Lanes and Pools

I was doing a training recently and the audience was predominantly technical. They knew WSDL, BPEL, JCA etc. One question that came up was why do we need lanes and pools. There is no implementation artifact being directly created based on lanes.
I could easily point that Pools are process boundaries, and I could see heads nodding. Even then questions remained about boundaries of pools. Then the question became why lanes?
At that point I realized that it is more important to emphasize the reason why people do BPM. It is not just to draw pretty pictures, it is :
to have a common understanding of processes;
to identify and document their processes as is;
to identify inter and intra departmental communications;
to find the bottlenecks;
to ensure that the processes as defined / documented is the same as implemented.

Once you see this value proposition of a BPM project, the value of pools and lanes becomes obvious. Pools help you identify the exact boundaries of your process. Pools will also show you inter-departmental communications - often the bottlenecks.
Lanes facilitate clear identification of roles and responsibilities within the organization. Identification of ownership of a given activity is at times the biggest reason why that activity will be performed in time. The intra communication points between various parts of your organization can be found using lanes.

That in summary is the value of using lanes and pools to document your process.