You'll have 900MHz 2G and 2100MHz UMTS 3G on Telstra and Vodafone, which isn't ideal if you're in an office building all day. High-frequency means low-penetration of buildings. You'll have good 2G coverage though. However, Vodafone are starting to make a new 900 MHz UMTS network in Australia's major cities, which would be great.
Also, the Pre 2 is probably the best choice if you want in on webOS phones right now. It's still the standard development device for webOS, so any continuing development by HP will be for tested for the Pre 2.