As part of a promotion for their new SkypeAccess service, which lets you buy Wi-Fi access using Skype credit on many Wi-Fi hotspots around the world, Skype is offering free Wi-Fi access at compatible locations everywhere all weekend. For Aussies that means early Saturday until early Monday.
The global list of compatible hotspot providers is found here, but the easiest way to find Australian spots with some confidence is by checking the lists at Boingo Wireless, one of the Skype Access partners. There's lots of Australian Wi-Fi spots that are part of this umbrella group.
The time runs 00:00 Saturday to 23:59 Sunday UTC. So do your local timezone maths from there. eg, AEST is 10:00 Saturday to 09:59 Monday. If you can find some local access, enjoy!