Apple has just released latest iPhone firmware 3.1.2 after firmware 3.1. In new firmware, no.of small bugs which were reported in firmware 3.1 have been taken care off, like iPhone getting stuck or crashed in middle of a running application.
It's recommended that all iPhone users who are on non-jailbroken version of Firmware 3.1 should upgrade to latest Firmware 3.1.2 even if they haven't observed any malfunctioning in Firmware 3.1 yet, as there is no harm in upgrading to latest software. You can easily upgrade your iPhone with latest firmware via iTunes. Just connect your iPhone with computer and start iTunes, it will prompt for downloading Firmware 3.1.2, click "Download and Install" and you are good to go.
Those of you who are on jailbroken/unlocked iPhone, should wait and NOT upgrade their iPhone to Firmware 3.1.2 till jailbroken version of this firmware is available. iPhone Dev Team has already shared a statement their latest jailbreaking tools (PwnageTool 3.1.3, Ultrasn0w) will not work with iPhone firmware 3.1.2. They also ensured that they will soon come up with appropriate method for jailbreaking on Firmware 3.1.2, however they didn't mention when it will be out
Update: iPhone Firmware 3.1.3 has been released by Apple, please download it from here.Contact Us for News Tips, Corrections and Feedback