I have seen it work both ways, as an advantage and a disadvantage. In my opinion, there are certain companies in Adelaide where being of Italian, Greek, Spanish heritage (for example and other nationalities) will help you get a job with them. Whether people choose to use that totheir advantage is up to them.
Some jobs I have secured, at the interview stage it has definitely been an advantage being a pom and for other jobs it has made no difference.
In my experience, your personality and the ability to ‘fit into the culture’ of an organisation has a big influence in the job application process. It is the same when dealing with recruitment agencies or contacts who may be able to assist you, people need to try and stand out (in a good way!) and build relationships without becoming a pain in the bum, it is a careful balancing act.