The important assumption is, that you are familiar with inter-portlet communication concepts like Public render parameters and Events, which is described in JSR-286 (http://jcp.org/en/jsr/detail?id=286).
Scenario described in chapter 8 extends the implicit behaviour, which should be implemented by every portal. For example you can use parameter bindings if you have portletA" with public render parameter "paramA" and "portletB" with public render parameter "portletB" and you need to wire these parameters with each other. So you can set "paramA" in processAction method in "portletA" and you can read this parameter as "paramB" in render method of "portletB". With default implicit behaviour, the both parameters need to have same name.
The possibility of different names "paramA" and "paramB" is enabled by parameter bindings. Event wirings and alias bindings concept are similar to this concept as well.
Use portal-coordination-samples if you need more inspiration. We will provide more useful sample portlets soon.
Thanks for your help. I really get quite useful suggestion.Now I'm reading the portal-coordination-samples.