I'm further confused by this page:
http://www.telecom.co.nz/content/0,3900,204798-203918,00.html
Mobile Broadband roaming is available in Australia's capital cities and selected regional centres, delivering speeds up to 2.4Mbps with average speeds of 300-600 kbps*.......
So, the webpage says it works, but everyone i know who has tried (2 people) say it doesn't.