As reported in the Dev Team IRC channel, Vodafone works. 3 works. (now just need Telstra + Optus/Virgin to be tested) 🙂

via iPhone 3G unlock – yellowsn0w is out! – MacTalk Forums.

See original source here.

AFAIK – all Australian telcos who support the iPhone work. This includes Telstra, Optus/Virgin, Vodafone, and 3.

I’m still deciding… Do I really need my iPhone AS A PHONE when I go overseas?

It can function perfectly otherwise… Just needs Wi-Fi for data (which is admittedly scarce where I am going), but otherwise, it’s a small iPod.