One of the most powerful features of Windows SharePoint Services (WSS) 2007 is workflow. I recently took a look at using Windows Workflow Foundation to create a Workflow to manage a complex process on SharePoint Portal Server for a client.
Windows SharePoint Services (WSS) 2007 is the first Microsoft server that has native support for the Windows Workflow Foundation (WF). Windows Workflow Foundation is the programming model, engine and tools for quickly building workflow enabled applications on Windows.
The integration of WF and the 2007 release of SharePoint provides an infrastructure that drives processes around SharePoint's strong suit: collaboration and sharing of information. This release focuses on document-centric workflows, the procedures that a particular document goes through in its lifecycle (be they reviewing, editing, or approval). The new edition enables you to attach and run a process directly in a SharePoint document or list item. Additionally, the workflows within SharePoint spotlight human-based endeavors, tasks driven by human interaction as opposed to static, automated programmatic steps.