There are at least 3 groups in Melbourne:
Calabrese Crime Family
Honoured Society
Carlton Crew

'Ndrangheta has Aus. divided up into 6 pieces: Adelaide, Melbourne, Griffith, Canberra, South Australia, New South Wales.

The Barbaro 'Ndrina is in Melbourne and Griffith.

Good updated info in this article:
http://www.theage.com.au/victoria/mafia-link-to-melbourne-pizza-wars-20140307-34cyp.html

There is an Irish group, Moran Family, in Melbourne as well..

That's about all I know without spending hours digging for things.