I then looked at the following website that is dedicated to Endangered Languages
http://www.endangeredlanguages.com/
It is described as "the world through 3054 lenses: an online collaborative effort to protect global linguistic diversity". I noticed that Wiradjuri is listed as "critically endangered, with 3 native speakers worldwide in 1981." They provide a document defining endangerment and extinction.
I am not sure that Wiradjuri is extinct or critically endangered:
In 2009 I learned Wiradjuri for a year and received a Certificate 1 in Wiradjuri from the NSW Technical and Further Education Commission of Australia. During this course I met and learned from Wiradjuri speakers.
Last week, I asked the authors of the Longitudinal Study of Indigenous Children if they knew of children on their project that spoke Wiradjuri. They said that there were.
UPDATE 20th August 2012
Laura Bennetts-Kneebone, the linguist on LSIC has just told me about AUSTLANG: The Australian Indigenous Languages Database. It shows that in the 2006 Australian census there were reported to be 102
speakers of Wiradjuri.
I look forward to working further to find out more about the actual status of Wiradjuri