With Chronic Dev Team's progress reports on iPhone OS 3.1 exploit and Jailbreak everybody was expecting them to take the lead with Greenpois0n jailbreaking utility coming before iPhone Dev Team release's their updated PwnageTool 3.1 compatible with Apple's latest 3.1 firmware update, however, the iPhone Dev Team has now once again taken the lead by releasing an updated version of PwnageTool 3.1 for MacOS X - the updated utility lets users jailbreak iPhone OS 3.1 by creating an custom IPSW file without updating the baseband and hence retaining the Ultrasn0w unlock and jailbreak.
The bad news is that the current release of PwnageTool 3.1 is available only for Mac OS X and supports iPhone 1st Generation (2G), iPhone 3G and the iPod Touch 1G only - that means no jailbreak for Windows and iPhone 3GS/iPod Touch 2G/iPod Touch 3G users as of now.