Java.net have a very brief overview of OSWorkflow from the Open Symphony group, an open source Workflow engine.
What is Workflow? Workflow is the ability to define ordered processing steps and tasks that need to occur as part of a business process. A Workflow engine should allow you to easily define these steps and tasks and then integrate the use of this engine into your system.
The article illustrates building the steps by hand as an XML file, but the project also has a graphical workflow editor, although this isn’t demonstrated in this article.