All you iPhone/iPod touch guys, a new firmware iPhone OS 3.1.3 is now out.
However this release is just a maintenance release I guess, with just bug fixes and patching security holes with no new features added to it. But it is highly recommended to upgrade to this version for security issues.
So Fire up iTunes on your desktop and update your iPhone’s firmware.
Note: This update will undo the jailbreaking process, so if you have a jailbroken iPhone/iPod touch I would recommend you to not upgrade to 3.1.3 immediately and wait for iPhone Dev team to jailbreak it.