no, afaik JBoss AS does not have jBPM by default but it is very easy to deploy it. Just download jBPM distribution and follow user guide. There is install directory with nice ant tasks that help you to start with jBPM very quickly.
You could look into another JBoss project if you thinking about orchestrating only web services: http://www.jboss.org/riftsaw
Or JBoss ESB
Unfortunately I am not the best person to compare these two, perhaps Ronald can give more valuable feedback on this.
In my opinion jBPM is more suited for transaction aware protocols to get most of it where Riftsaw is better choice for loosely coupled solution such as WS since it focuses on BPEL (WS-BPEL) implementation.
I would say that it is difficult to compare them, it really depends on your needs. But I think that jBPM is a bit more flexible since you can utilize WS in it as well.
Correct, it's kind of service orchestration (aka microflows) vs process/business flows
in which there is a reference to an aticle by Tom Baeyens, initiator, project lead and one of the developers of jBPM