On Sat, 06 Oct 2007 19:04:25 -0700, Noodle wrote
in .com :

Report all illegal immigrants, workers & backpackers in Australia:

1800-009-623 or
+61-2-6264-1111

Had a quick look at Google with the search term
"1800-000-623" reward
and couldn't find any Gov't source that promised a reward.

However, on Googling just phone number in quotes, one
interesting site mentioned penalties for those who violated
the law:
Australian Immigration Fact Sheet 87
http://www.immi.gov.au/media/fact-sheets/87illegal.htm

The penalties mentioned are pretty heavy, involving
fines, gaol, deportation, etc.

The 10 page PDF download gives more detailed info, case studies,
etc. but still no mention of rewards that I could see.

The new penalties came into effect 17 August 2007 and IMHO, the
longer one is worth reading.

Cheers,