Comex, an iPhone hacker, has promised to release jailbreak tool for iPhone 3.1.3 firmware. He has been working on Spirit tool, which works on userland jailbreak technique.
As said by hacker, the Spirit tool supports all iDevices i.e iPod Touch, iPhone and iPad. In a conversation over Twitter, he has confirmed that the tool will be released on this Friday.
Spirit tool successfully jailbreak iPad 3.2 and iPhone 3.1.3 firmware. However, it will only be useful for activated devices. On the other side, it is just a jailbreak tool which also means you can not unlock your iPhone 3G and iPhone 3GS. No other hacker has announced the unlock tool for iPhone 3.1.3.
Some hackers are actually waiting for iPhone OS 4 final release so that they can use the valuable exploit for the new OS. Now, we can’t do anything about it. Those who have updated their iPhones to iPhone 3.1.3 will have to wait till WWDC event.
Apple has also released an updated iTunes 9.1.1 version, but I would recommend you to stay away from it. Although Hackers are saying that there should not be any problem with the new iTunes, it is quite safe to be on old version.
Update: Spirit Jailbreak Tool is NOT releasing today. [Link]