The iPhone Dev-Team has just confirmed (sort of.) that they are working on a new version of PwnageTool which will enable iPhone 3G and iPhone 3GS users to jailbreak iPhone 3.1.3 firmware without having to update their baseband. For those of you who don’t know, PwnageTool, like Sn0wbreeze is an iPhone jailbreaking tool which creates custom .ipsw files without the upgraded baseband. These custom .ipsw firmware files created with PwnageTool can then update iPhone to the latest firmware (iPhone 3.1.3) without updating its baseband so that it can be unlocked to run on any carrier SIM using either ultrasn0w or blacksn0w. In a nutshell, PwnageTool for Mac is what Sn0wbreeze is for Windows users.
Any ETA on PwnageTool for iPhone 3.1.3 is not known yet, but judging from Dev-Team’s past work, it shouldn’t be too long before it is released.