This is a great blog by Kurt Stam on the ESB Core team that describes the benefits of using jBPM to have a single end-to-end process flow that incorporates both service orchestration and human-task management.
There is very real synergy between bringing BPM capabilities services world.
Please take a look and give us your feedback.
That's in process currently, right? What about remote invocations? I.e. ESB and jBPM on different hosts?