This update for iPhone and iPod touch contains bug fixes and improvements, including the following:

• Improves the accuracy of reported battery level on iPhone 3GS
• Resolves issue where third-party apps would not launch in some instances
• Fixes bug that may cause an app to crash when using the Japanese Kana keyboard

Jailbreakers BEWARE:

The iPhone Dev Team have warned via their Twitter account that updating to 3.1.3 will not only lose your jailbreak, but it may also prevent you from using the Ultrasn0w and Blacksn0w unlocks for the 3.1.2 baseband on the iPhone 3G and 3GS. It may also brick iPhone 3GS and third-generation iPod touch models that require Apple’s signature checking (SHSH) for restoring in iTunes.

We will keep you updated here as more information rolls out about this latest firmware update. For now, stay tuned to the iPhone Dev Team for their green light to update once they release the necessary tools. (PwnageTool, Redsn0w, unlocks if available).

From the logs, we can only tell about the existence of iPhone firmware 3.1.3 but there’s no info about the features. One thing is for sure that major features can only be found in OS 4.0. iPhone 3.1.3 firmware will just bring bug fixes. We can expect iPhone firmware 3.1.3 any day now but the major release – iPhone OS 4.0 will be released next year around March.

Warning!

If you’re using a jailbroken or an unlocked iPhone, you better stay away from any upcoming firmware update or you would lose your jailbreak and unlock.