Due to the lack of a better post, and equally, the boredom of a geek’s Saturday night, I have found this guide. It shows you how to unlock your iPhone with the 3.1.3 firmware using Blacksn0w. It only unlocks the phone but doesn’t jailbreak it. Fortunately, there’s another guide for that. It uses Sn0wbreeze. As for me, I’m still running 3.1.2 until I get really, really bored. So far, 3.1.2 still does what it’s supposed to.

Unlock Guide for 3.1.3

Jailbreak Guide for 3.1.3