I expressed wealth inequality by looking at the percentage wealth the top and bottom 10% of people controlled. (And you can extend that to everything inbetween as well)
i.e
The top 10% control 70% of the wealth
The bottom 10% control 4% of the wealth...
etc etc.
Just like what you can also do with income. (i.e
http://www.colorado.edu/AmStudies/lewis/ecology/incomegr.gif ) Its a good way of showing both income AND wealth inequality.
I'm not sure of the exact wealth figures for Australia. Google.
I have a nice graph in one of my textbooks which shows Australian wealth distribution (By looking at the ownership of assets)