When Apple released OS 3.1.2, many of the jailbreaking applications for the iPhone and iPod Touch stopped working. However, several developers were able to come out with workarounds for the patch, the first being blackra1n followed by PwnageTool and most recently by sn0wbreeze.
Now another iPhone jailbreaking tool Redsn0w has been able to come up with an update ahead of the announcement of iPhone OS 4.0 at the Apple Event on January 27th. The update to Redsn0w allows users to jailbreak their iPhone or iPod Touch running iPhone OS 3.0 and 3.1.2. Almost every version of device is supported in this beta update, except for the iPod Touch 3G.
The software also supports carrier unlock for iPhone 2G. However other users will have to install Cydia, and then use it download install ultrasn0w (baseband 04.26) or blacksn0w (baseband 05.11). Redsn0w is currently available for both Windows and Mac based PCs.
Users of iPhone 3G will have to wait for the final release of Redsn0w to jailbreak their devices. For installation instructions and downloads visit this page.