Vodafone Australia on Friday, July 6th has released the maintenance update for their version of Samsung Galaxy S III. The update is designed to fix bugs, improve performance and stability. Your device will remain at the Android 4.0.4 version, it will see some stability and performance improvements.
The update will not be available for everyone at the same time, it will be released gradually. You can get the update by connecting your phone to PC and use Firmware Upgrade option in Tools menu of Samsung Kies. Over-the-air update will be available at some later date.
SOURCE: Vodafone Blog