jPDL stands for Java Process Definition Language. It is an interesting technology that allows business processes or workflows to be diagrammed at a high level, one which even a business person may be able to follow with a little help. I can’t help but think of Jira when they talk about states, transitions, etc. Jira is a classic example of workflow, and often in applications we build there are also elements of workflow. If you are writing state transition diagrams during design it is a good indicator that you have workflow.
In jPDL the diagramming tools are manipulating the XML that defines the workflow that the code will read in and parse at execution time. There is an Eclipse plugin that handles both graphical and direct editing of the XML. It has some nice features like generation of forms (or scaffolding I would probably call it since there is still a large amount of work to make it look pretty) based on the diagrams, which could help you get the application up and running quite quickly.
I am sure that the devil is in the detail and the session didn’t go into too much technical details. However, if your solution has strong workflow aspects I think it is well worth checking it out.