PwnageTool 3.1.5 has been released by Dev Team, to jailbreak iPhone 2G, also iPhone 3G and 3GS but for only Bootroom and 04.26.08 as its baseband, and not just for iPhone but PwnageTool 3.1.5 can be used to jailbreak iPod touch too like 1G, 2G non-MC model that have not been jailbroken yet, with this tool you can create customize iPhone 3.1.3 firmware version and no need to update the baseband

But remember that PwnageTool 3.1.5 does not work for Windows OS, such as Vista, XP and windows 7, it’s solely for Mac OS, if you are Windows users you can use Sn0wBreeze v1.5 to jailbreak your iPhone running on iPhone 3.1.3 firmware

Do these to Jailbreak iPhone 3.1.3 using PwnageTool 3.1.5

1. Download PwnageTool 3.1.5 or to the direct download link here
2. Download the following according your iPhone type:
   For iPhone 2G Download iPhone 3.1.3 firmware
   For iPhone 3G Download iPhone 3.1.3 firmware
   For iPhone 3GS Download iPhone 3.1.3 firmware
3. Go to this page to Jailbreak iPhone With PwnageTool For Mac