In reply to Richard.

Richard, you are correct that currently no Australian postal address geocoding lookup file is available for download. However, free Australia Post postcode boundaries are available from the Australian Bureau of Statistics (ABS) in their Postal Areas (POA) file - take a look at this link http://support.sas.com/rnd/datavisualization/mapsonline/html/geocode.html. You are also correct that there is Google geocoding available via their Google Map API.