One chapter in Pragmatic Programmer recommends looking at a blackboard/space-based architecture + a rules engine as a more flexible alternative to a traditional workflow system.
Why do you regard Javaspaces as dead, beyond the fact that the Jini 2.1 release was some time ago (October 2005) ? Having used that, I'd suggest that it indicates a mature and complete technology set rather than something abandoned and defunct.
For another implementation of Javaspaces, take a look at Blitz Javaspaces. That's maintained and enhanced more regularly (latest release July 2008) and offers a more performant and manageable Javaspace implementation than the default outrigger
supplied by Sun.