Niantic has posted a new blog post and has announced that Pokémon GO field testing will expand to Australia and New Zealand later in April 2016. Below is the press release from that blog post.

Pokémon GO field testing expands to Australia and New Zealand

April 7, 2016 - The Pokémon Company and Niantic invite users to field test Pokémon GO in Australia and New Zealand. Users can visit http://pokemongo.nianticlabs.com to sign up. Please note that sign up doesn’t guarantee access to the field test. The Pokémon GO field test will give users the opportunity to share early feedback and help improve the Pokémon GO experience.

Thank you for your interest in Pokémon GO.

— The Pokémon GO Development Team

Sources: http://www.nianticlabs.com/blog/pokemon-fieldtest-au-nz/ and https://twitter.com/NianticLabs/status/718212114842841088