How to Jailbreak 3.1.3 iPhone 3G & iPod Touch 1G/2G Windows & OS X
This guide teaches you how to jailbreak the latest Apple firmware 3.1.3 for the iPhone 3G, iPod Touch 1G, and older iPod Touch 2G using the redsn0w 3.1.2 loophole.
Before we begin there are some things you need to know. First of all for the iPhone 3GS, iPod Touch 3G, and the newer iPod Touch 2G (model number beginning with "MC") jailbreaking 3.1.3 is NOT POSSIBLE at the moment. Do not try. We strongly recommend you DO NOT upgrade to 3.1.3 if you use one of these devices.
Update: Again just to make sure it's painfully obvious . . . You can not jailbreak 3.1.3 for the following devices: