A month before Apple has released iPhone OS 3.1 and now the  iPhone OS 3.1.2 update is out for iPhone and iPod Touch users. The following fixes are mainly included in iPhone OS 3.1.2 version as:

• Resolves sporadic issue that may cause iPhone to not wake from sleep
• Resolves intermittent issue that may interrupt cellular network services until restart
• Fixes bug that could cause occasional crash during video streaming

The weight if iPhone OS 3.1.2 is 241.7 MB, so just attach your iPhone or iPod Touch to your computer, go to iTunes and it’ll automatically ask for the iPhone OS 3.1.2 update, so proceed further to complete the update process and enjoy.

The owners of jailbroken or unlocked devices must have to wait for an update by iPhone Dev Team.