There has been some time that about the risk in jailbreaking for the firmware version 3.1.3 so there is now a  Untethered Jailbreak for iPhone Firmware 3.1.3 and a demo video that will demonstrate how to jailbreak iPhone 3.1.3 firmware using a bug in 3.1.3 firmware and which will guide how to jailbreak your iphone safely..

Comex has developed a new Untethered jailbreaking hack and also has prepared a demo video that explains the untethered jailbreaking. with this hack user will be able to  jailbreak their iPhone simply by pointing to a website instead of loading an exploit to the kernel, hence the Userland terminology.

iPhone Dev Team has confirmed that this Jailbreak is authentic and working. However, the detailed how to tutorial and the release date is yet to be announced by Comex.