afaik, this is not a jboss issue, but a jbpm issue. And afaik jbpm can already do this. not via a webui or something, but from ant tasks it is possible.
Do you mean a 'process management/versioning ui' when you refere to 'manage the deployment of PAR's in production?
What I seem to recall hearing about was a way to drop a PAR file in the deploy directory (or something under it), and have the process auto-deploy from there.
Taking the Ant task approach (which I now am, sort of), this becomes exclusively a jBPM issue, like you said. I wasn't sure ahead of time if the hypothetical automagic deploy feature might have used JBoss' deployment scanner, though, so I had the two products joined at the hip.
What I was looking for doesn't totally make sense to me upon further reflection. JBoss would have no concept of "deploying" a PAR, since (if I am not mistaken), it only deploys things which have some J2EE-defined concept of Being Deployed. (Not counting SARs, which are special. :))
Somewhat separately, is there a definitive reference for the PAR file format anywhere online? I've read section 13.1 in the documentation, but some questions remained (like how to package code in a PAR).