Digging in the server log, I found this:
So clearly something else is already using port 8080 (what is, I have no idea, it's a completely clean system, new OS install). So I guess I have to dig around and either (a) try to find what's using 8080 and shut it down or (b) move the server process to another address. Option (b) might be easier if I can find where to configure jBPM.
Thanks for the help!