As part of Qantas Grand Prix Sale, currently on Domestic and International Flights.
From experience, sale may end sooner than stated on their site (21 March).
Works out to be ~$800 return for a return flight to Hong Kong (Qantas - includes checked in bags, meals, in-flight entertainment, QFF points etc.) which I think is a great deal.
Travel Periods:
01 May 2012 - 31 May 2012
01 Aug 2012 - 31 Aug 2012
A few other specials worth mentioning (have different Travel Periods to HKG deal, prices shown from SYD although generally looks to be the same as MEL/BNE/ADL):
Shanghai (Pudong) - $399 one way
Mumbai - $999 return
Johannesburg - $1599 return
Damn no perth-hkg lei