According to BBC Worldwide:
It’s always been our ambition to work with our broadcast partners so that international Doctor Who fans can enjoy the 50th Anniversary special at the same time as the UK. We’ll have more details soon about our very exciting global plans for November.
The UK screening is set for 8pm on Saturday November 23rd, which means 6am in Sydney on Sunday 24th. The US gets a slightly better deal with noon screenings on the West Coast, 3pm on the East.
We’re still awaiting official word on where and when the cinema screenings will take place, or which of the international broadcasters will be showing the episode in 3D.