Since Nate True's now less than recommended jailbreak was released just days ago, there have been a few new incarnations of 1.1.3 jailbreak methods - including the first officially sanctioned by the iPhone Dev Team. As each new jailbreak method is released, things get progressively easier for the iPhone owner. The latest method, from the iPhone Dev Team, makes having a jailbroken 1.1.3 iPhone incredibly easy.
This new jailbreak is completed without the use of a PC. The jailbreak does require that your iPhone already be jailbroken and running iPhone firmware 1.1.2. Other than that, it's smooth sailing. All the necessary steps are completed automatically OTA (over the air).
To complete the process, you need only open up Installer.app on your 1.1.2 iPhone and install "Official 1.1.3 Upgrader.". The rest will happen automatically. You must be connected to a charge source and WiFi.For any questions related to the 1.1.3 jailbreak process, we highly recommend iPhoneAtlas' 1.1.3 Jailbreak Guide.