Unlike US customers, Australian customers generally don't need to pay extra for tethering when using an iPhone 4 as a wireless hotspot. But there's one plan where you should be cautious: the Infinite plans launched by Vodafone last November don't allow their included data to be used for tethering.
Included data excludes tethering. Additional data usage rate is $0.25/MB (min 50KB session).
That restriction would affect not just iPhone owners, but also Android customers. The lesson? If you do want a Vodafone deal (and yes, that in itself might seem odd) and you're thinking tethering will be important, then its standard cap plans are the only option to consider. Thanks John!