Apple has updated the iPhone OS to v3.1.3. Being an update on the same v3, this doesn’t bring drastic improvements but promises to do some things right. For instance, it will improve accuracy of reported battery level on iPhone 3GS, resolve third-party apps launch issue and fixes app crash using Japanese Kana keyboard.
For those looking to jailbreak, iPhone Dev reports that redsn0w is still compatible with the new firmware but 2G (with MC model), 3G iPod touch users and iPhone unlockers should stay away from it. More info on the jailbreak here.
The firmware is available on iTunes and is compatible with all iPod touch and iPhone models.