Back in Service Design, we describe the process of Service Catalog Management and the notions of the Business Service Catalog and the Technical Service Catalog. Business Service Catalogs describe the menu of service options available to customers, and Technical Service Catalogs describe the "cookbook", or procedures to provision and deliver the service. By publishing the Business Service Catalog, we make the services more transparent and available to the users. By publishing the Technical Service Catalog to our technical/functional teams, we provide the basis for consistent policies and procedures in deploying these standard services.
The role then of the Request Fulfillment process is to facilitate using these. A heavy emphasis in the books is on automating workflow activities; automating service requests and Financial and Compliance approvals on the client side, and automating provisioning and configuration management activities on the IT side. We can then use our understanding of lifecycle management to break down the process activities, and then look to leverage workflow management and automation tools to speed these through.
Even though Incident Management gets all the press (after all, it's when fires happen that people actually notice IT), Request Fulfillment is the key to maturing your provisioning activities and ultimately in freeing up Operational resources that can be reinvested in more proactive service activities such as Problem Management, Testing and Validation, and Service planning.