While it won’t immediately arrive in Australia (due to a combination of different hardware and carrier testing for carrier-sourced models), it appears that HTC is on the cusp of keeping its promise to deliver Android 5.0 Lollipop to HTC One (M8) owners within 90 days of the code hitting AOSP.
In the US, HTC is releasing the update for unlocked handsets and the One (M8) Developer Edition handsets. The update comes in at 584.83MB and brings the One (M8) software version to 4.16.1540.8 and Android 5.0.1 with Sense 6.0.
If you absolutely can’t wait for the update to arrive in Australia, my advice would be to keep an eye on the XDA Developers HTC One M8 forum, because give it a day or so, and someone will have captured the OTA, created a generic ROM that’ll work on any One M8, and uploaded it.
Otherwise, sit tight. It won’t be too long now. Hopefully.