Salesforce is doing their annual event as part of CeBIT Sydney this year. CeBIT is a three-day event; the official Salesforce.com events are occuring on the first day but the Salesforce expo hall will be open for all three days as well. You'll need to register here for your free pass.
This is a community-driven Meetup that is used to publicise Salesforce.com-related events of interest to people in Melbourne. There are three official user groups in Melbourne: the general Salesforce.com User Group, the Not-For-Profit User Group, and the Force.com Platform Developer Group. There are also generally a few official annual Salesforce.com events in Melbourne like Cloudforce Essentials, and occasional general SaaS events that may be of interest to Salesforce.com people. This Meetup is an unofficial channel to notify all Salesforce.com community members about any event that may be of interest.