From what I can say: discussion on the future of jBPM just started on the mailing list. I am getting the idea that Drools and jBPM should be joined in one project to offer a more complete solution - but how this is going has not been decided yet. Sometimes I am getting the impression it has been - in this case the discussion on the developer's mailing list would be useless. For me there is still the chance that jBPM 5 will be based-up on parts of jBPM 4. It offers the PVM to also support Drools Flow and after all Drools in first place is still a java rule engine based up-on the rete algorithm IMHO. jBPM 4 is not bad - not just yet finished. I think there is already a kind of consensus that users should be enabled to just use the rules engine and the process engine of jBPM 5 without having to deal with both of them.