Australians spend 1 in 5 minutes using social media sites. Social Networking usage was about 22% in December 2010 says comScore.
The statistics reveal that Facebook, Twitter, LinkedIn are some of the most popular destinations. If you add into this instant messaging then the total rises to 35% - which is probably a more realistic definition of social networking.
There is a presentation you can download with really good insights on internet usage across Australia.