ugh, jailbreaking and unlocking are not the same thing. Jailbreaking = removing Apple's software restriction so that you can install any software you wish to install that is not authorized by Apple and on iTunes app store. Unlocking = Removing the carrier restriction on the device so that you may use it on any compatible network. IE: GSM device on any GSM network and CDMA device on any CDMA network.
Get the EVO 4G. Forget the iPhone.