only in 3.2, you'll be able to configure jBPM to use JMS. (and then you can configure any JMS provider in the back).
It requires some coding in 3.1.x to bind the jbpm MessageService to JMS.
You can look at the 3.2 implementation in CVS and just copy/compile/use that in your own environment.
Thanks for the information Tom.
When is JBPM 3.2 releasing?
the plan is to release 3.2 around newyear