The iPhone Dev-Team has released PwnageTool 3.1.4, an update to its Mac hacking utility for iPhones and iPods. The group also confirms rumors that Apple may be finding ways to block future jailbreaks.
This version of the PwnageTool was created to specifically unlock iPhone OS 3.1.2, but all generations of the iPhone are supported by this release as well as the first and second generations of the iPod Touch. (Second-generation devices must have already been jailbroken for this application to work.) Unfortunately, third-generation iPod Touch users are completely left out--no jailbreak for you with this utility.
According to the Dev-Team, iPhone 3GS users can jailbreak and unlock iPhone OS 3.1.2 using PwanageTool, but there is a catch: it will only keep the unlock for the cellular baseband intact if you have been jailbreaking and unlocking your iPhone 3GS using custom IPSW files beginning with iPhone OS 3.0 or earlier. (If that describes your situation, all you have to do is install ultrasn0w via Cydia after you perform a restore using one of the no-baseband-alterations custom IPSW's you created previously.)
In closely related news, iClarified also reports that Apple began shipping last week a new Bootrom, iBoot-359.3.2, which is not vulnerable to the 24kpwn exploit. In other words, newly purchased iPhone 3GS units may be protected against jailbreaks.
Finally, the Dev-Team recommends that 3GS users get and save their ECID hashes for iPhone OS 3.1.2 now, since this could be an important component of future jailbreaking efforts. If you've installed Blackra1n using our tutorial and are encountering problems with mobilesubstrate, winterboard, diskaid, or ifunbox, the Dev-Team has some custom IPSWs that can help. They also warn Blackra1n iPhone 3G and 3GS users that if the stock 3.1.2 firmware is used, there is no short-term unlocking solution. The Dev-Team is still working on hacks for the latest iPhone basebands.