UPDATE: EB Games Australia has just announced the Pokémon Go Plus is available to preorder on September 12 at 12PM AEST and will cost $49.95AUD. – Source
After the success that was Pokémon GO, there was also talk of a wearable device coming to wrists some time in late 2016. That time is coming in the form of Pokémon GO Plus, a small, wearable device that will let players interact with Pokémon GO without constantly looking at their smartphones.
Compatible with both iOS and Android*, Pokémon GO Plus connects to smartphones via Bluetooth low energy and notifies players about nearby Pokémon and PokéStops. When a Pokémon is near, the device will vibrate and its LED will flash green**. Players can press the button on the device once close to throw a PokéBall. A successful catch will result in the device flashing and vibrating. – Press Release From Nintendo Australia
For those Pokémon trainers able to wait a little bit longer, Niantic has also announced an Apple Watch companion App which will display nearby Pokémon, alert you when wild Pokémon appear and monitor the distance required to hatch eggs. The Pokémon GO App is set to be released by the end of this year.
*Please refer to compatibility information on Pokémon GO Plus Support site.
**Pokémon GO Plus is unable to provide an alert for any Pokémon attracted by the in-game item Incense.