It never takes long for the Dev Team to pry open the seams of the latest iPhone OS firmware, tickle its insides and come up with a fresh Jailbreak. Less than a week after Apple released their iPhone OS 3.1.3 update, the Dev Team followed it up with an update of their own: Pwnage Tool 3.1.5.
Here’s the caveat: the iPhone OS 3.1.3 update was pretty insignificant. The only real bug fix for non-Japanese users was improvement of the battery life indicator in rare cases. If you haven’t noticed a problem with your jailbroken phone, especially an iPhone 3G or 3Gs, you shouldn’t upgrade, since if you mess up your Pwnage, you risk losing your carrier unlock forever.