It looks like the process instances started but it failed during execution. First line of the log file is:
2011-09-28 07:34:00,547 INFO [STDOUT] (http-localhost%2F127.0.0.1-8080-4) Hello World
Then is continued to execute the process exception was thrown because of missing orm file of jbpm-persistence-jpa. Make sure you have that file, it contains the named query that is mentioned in the stack trace.