I'm using the last posted AusPost module and it seems to be working ok, though the store hasn't gone live yet, so it hasn't been tested to heavily.

GST is still a sticking point for me. In reading other posts it seems like the only way to make it work 100% how it should be, core has to be modified and I'm not sure that's something the Ubercart team wants to do. The system just isn't built so that prices can be shown including tax and that the tax just shows as a value showing the tax included. I think there are a couple people who have looked at this and have modified core to be able to do it. Luckily with the store I'm using, they want to calculate the tax as it is done in the US, with the prices being without tax, and the tax being included in the end. That makes it easy for the tax to only be included if the person is in Australia, but if someone comes to me and wants the GST to show as included in the price, I'm going to be in trouble, haha.

Cheers,
Steph