interesting article from Gilbert & Tobin.
We often have to give both patent and design registration advice to clients. It's important to remember that there is no grace period for filing an application to register a design in Australia. So applicants must either file in the first instance while the design is still confidential or make use of the 6 month convention period as provided in the Paris Convention.
At the end of the day, the rule remains: keep it secret until you have had a discussion with your patent attorney.
Here is some more information on the registration of designs - http://beagar.com.au/Registered%20Designs.htm