OpenWFE is an open source workflow engine. It's written mainly in java and it's released under a BSD licence.
OpenWFE 1.5.3 introduces new features like a workitem modification tracker (sponsored by http://www.obinary.com\), disptaching of workitems over SMTP, and a simple set of classes for embedding an OpenWFE engine.
Important bugs got fixed that affected max size of dispatchable workitems, as well as a timer bug in the expression pool (engine rundata).
This is an important maturity release.