The Australian National University is piloting the use of the uniTEST aptitude test in 2007. Monash University tried it in 2006.
There are some test questions to try online, about: Dealing with information, Problem Solving, Decision Making, Argumentative analysis, Interpretation and "Socio-cultural understanding". I tried the test questions and they are not easy.
The tests allow those with a lower entrance rank to improve their chances and is available to international as well as domestic students.