• Supanova Sydney, which takes place June 13-15.
• and Supanova Perth, which is June 20-22.
You can find more details at the big damn Supanova Expo website; dates and times for signings are up, schedule for his Q&As are still pending. Autographs are AU$30, photo ops AU$40. Also, as per usual: any convention appearance is subject to his availability at that time and a film or TV commitment could force him to cancel.
(Thank you meshel73 for the heads up! :) )