http://wikitravel.org/en/Australia#Electricity
Please refer to above site.
Australia is officially 230V - not 240V, was changed with the introduction of AS60038-2000 - frequency 50Hz.
Many laptops, shavers and iPod-type chargers can handle both voltages and frequencies.
Most electrical items from Hong Kong can be used in Australia. Just remember to bring an adapter. It is the same as those used in China, with 3 flat blades set in a triangle.