JBoss jBPM is a flexible, extensible workflow management system. jBPM combines easy development of workflow-applications with excellent enterprise application integration (EAI) capabilities. it includes a web-application and a scheduler and can be used in the simplest environment like an ant task and scale up to a clustered J2EE application.
The jBPM enables the creation of a workflow management system that bridges the gap between managers and developers by giving them a common language: the JBoss jBPM Process definition language (jPdl).
This article is an introduction and hopefully will help you start using JBPM easily and fast enough. As a first step you can take a look at this reference jbpm reference guide