The main problem for me is that my installer zip file, jbpm-5.2.0.Final-installer-full.zip, doesn't contain any sql scripts for mysql.
The documentation in this thread was insufficient to get that version working with mysql. I found out that in the included jboss 7 you need to install the mysql driver as described in http://planet.jboss.org/view/post.seam?post=how_to_create_and_manage_datasources_in_as7. In jboss as 7 apparently the jbpm datasource is defined in standalone.xml, and I'm about sure that a port to mysql cannot be achieved without changing that file too.
Puzzling all pieces together I currently have a 5.2.0 working on mysql, the only remaining problem is that in the demo scenario the workflow diagram always remains in the start state, even when krisv did a self evaluation.
My gut feeling is that 5.2 is not production quality yet today, I'll create a separate post to see what the rest of the world thinks about this ...