One season (or more) behind. We didn't get the full-on Maxi dresses craze yet, so be a pioneer and pave the way for Oz!
For some reason, I find it really hard to get 100% natural fabric tops a decent prices, so I'd bring some smart cotton tops/vests and linen trousers.
The high street shops are very much the same (Country Road, Witchery, Saab, Sportscraft etc.) but online shopping for national stores / designers has improved a lot in the last couple of years.
Myer and David Jones are releasing some really nice (and cheap) designer diffusion lines from Nicola Finetti, Zampatti etc. and if you really love exercise, check out the Canadian brand Lululemon for super quality lounge / sports wear.
You can seriously get amazing "pieces" (how pretentious am i?) from young designers in the markets and a lot of the big international names started like that in Oz. Affordable prices and very avant-garde. Also helps avoiding the "country road" syndrome, with everyone rocking up to work wearing the same thing.
Best of all, Victoria Secret is here (lovely clothing, not just lingerie) and praise the fashion-gods.... Zara is finally opening their Australian operations! (just in time for my return to the UK - blah)
HTH and sorry for the essay!