IP Australia and the US PTO have reached agreement to permit some international searching for US patent applications to be undertaken by IP Australia.
According to IP Australia:
The arrangement, which comes into effect on 1 November 2008, will allow applicants from the US to choose IP Australia to undertake the initial search and examination of their patent application under the Patent Cooperation Treaty (PCT). Applications that may not be covered under the arrangement are certain international applications relating to particular mechanical engineering or analogous fields of technology.
The arrangement starts on 1 November 2008.
A bit more detail here. Nothing on USPTO site as yet.