This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Headers in SOAP messages can be used to send out-of-band information with a SOAP message, such as security credentials, transaction information etc.
There once was an idea that SOAP messages could be send not only directly from client to server, but passing a number of intermediary nodes along the way to the server.
Each node along the way can have a role (more like a name) that can be used to target headers to a specific node.
In reality, I rarely, if ever, see intermediary nodes.