Well, it seems the Vodafone Australia has just released its iPhone plans and surprisingly, they are even more expensive than Optus' plans.
Starting at $69 per month (plus $189 for the 8GB or $309 for the 16GB iPhone), you get just 250MB of monthly data. To get 1GB of monthly data, you need to spring for the $169 per month plan which, on the plus side, gets you a 16GB iPhone for free.
Considering Vodafone were the first Australian carrier to offer a 5GB modem plan for just $39 per month, this is very disappointing.
Oh well, seems like we only have Telstra's plans left to see. At least Telstra have committed to free wireless at all their hotspots (most McDonalds and Starbucks locations).