Apart from the popular $49 cap for the iPhone from Optus, here are some of the other iPhone caps:

Optus $59 ‘yes’ Cap Plan for iPhone 3G

Monthly fee: $59
Included value: $350 calls and text
Data allowance: 500MB for mobile internet data
iPhone 3G 8GB model monthly fee: $0 on 24 month contract, $35 on 12 month contract
iPhone 3G 16GB model monthly fee: $9 on 24 month contract, $46 on 12 month contract

Optus $79 ‘yes’ Cap Plan for iPhone 3G

Monthly fee: $79
Included value: $550 calls, unlimited text
Data allowance: 700MB for mobile internet data
iPhone 3G 8GB model monthly fee: $0 on 24 month contract, $30 on 12 month contract
iPhone 3G 16GB model monthly fee: $4 on 24 month contract, $41 on 12 month contract