Hi Fernando,
you can always use the trunk:
svn co http://anonsvn.jboss.org/repos/jbpm/jbpm4/trunk jbpm4
mvn install
I found the jbpm4 trunk to be very stable and usable.
I doubt there will be a new release anytime soon, there haven't been much commits lately and not much people working on it either, you should read this thread in case you haven't yet: jBPM 4 is dead?