If you are married, you either file for the immigrant visa or the K-3 to enter the US to apply for adjustment of status. As your US citizen wife will be lawfully residing in Australia (I presume), the US consulate there should have jurisdiction to accept a direct filing of the I-130 relative petition. Contact the consulate or embassy directly to confirm she can file there. If not, she files it with the USCIS in the US.
Answered on Jul 26th, 2011 at 4:10 PM