SWF is awesome, but it can feel very abstract for most use-cases. In light of this, one of my good colleagues wrote a library called Super Simple Worfklow. It provides the level of simplicity that one would have expected from SWF to begin with. We opened sourced it at my company, check it out[1]. We use this library for production services.
(Full disclosure: I work at Bazaarvoice, and my colleague does, too!)