Yes, you can do it with the current version of jBPM.
You can assign tasks to a single actor or you can assign tasks to a pool of actors. If you use one pool of actors for each role of users, then all users with the given role could execute the task, but only one of them will execute the task.
I don't know what 'voting' means but I think you could do it by developing your own AssignmentHandler.
More info at: http://docs.jboss.com/jbpm/v3/userguide/taskmanagement.html#assignment