This puts all the other iPhone plans from all the other carriers to shame. Dan Warne over at APC has discovered a loophole in Telstra's cap plan structure that allows you to get 6GB of data plus a $49 cap plan for the iPhone 4 for just $78.50 over 24 months.
The reason for the loophole is that Telstra bundles both data and voice calls in their payment plans, but users who want more can remove the bundled data from their plan of choice and add on a data pack with a 50% discount.
Telstra have confirmed that these plans are legit, even though they won't be actively promoting them. Considering Telstra's promised that their next batch of iPhone 4 handsets would be available today, this is probably the best deal you're going to get if you're after a data-heavy plan.
Check out the APC article to see a more thorough breakdown of the loophole plans.