Spiff Workflow is a library implementing a framework for workflows. It is based on http://www.workflowpatterns.com and implemented in pure Python.
In addition, Spiff Workflow provides a parser and workflow emulation layer that can be used to create executable Spiff Workflow specifications from Business Process Model and Notation (BPMN) documents.
For documentation please refer to:
Mailing List: http://groups.google.com/group/spiff-devel/