Until recently, it was a requirement that, in order to invoke the PPH at the USPTO, the office of first filing (OFF) could not be the USPTO. This meant that an unconventional filing strategy (i.e. a non-US first filing) was required in order to make the PPH available to US clients.
Last month, the USPTO relaxed the requirement that the OFF could not be the USPTO such that, under the new regime, any un-examined US application sharing a common priority with an allowed Australian application may now be fast-tracked at the USPTO under the PPH. The USPTO revised requirements regarding the PPH can be found here -
http://www.uspto.gov/patents/init_events/pph/pph-mottainai_ipau.pdf
Note the availability of an expedited examination process in AU which means that allowance in AU can often be achieved very quickly.
Please let us know if you have any queries.
Regards, Bill
PIZZEYS
bbennett@pizzeys.com.au