If you already have the iPhone OS 3.1.2 and wanted to jailbreak it, there is some real great news for you guys: Blackra1n has just been announced by GeoHot. This does come with a strict warning: it does NOT mean you can unlock your iPhone and moreover, if you have iPhone OS 3.0.1 or 3.0, you should not be using Blackra1n at the moment.
Official Update (June 23, 2010): Official iOS 4 Jailbreak for iPhone 3GS, iPhone 3G and iPod Touch 2G from the iPhone Dev Team.
If you have the previous versions, you would need to wait till the next version of the PwnageTool is unveiled. Moreover, only the Windows version of the Blackra1n is launched and the Mac version is expected in sometime. You could go ahead and take a look at the step-by-step instructions for using the jailbreak tool at iPhone Download Blog.
Geohot’s Blackra1n jailbreak allows you to open up iPhone OS 3.1.2 devices like iPod touch 3G and new iPhone 3GSs falling short of unlocking though. You really must make sure which version of the iPhone OS you are using and if you have already done a jailbreak previously, and make sure to read the step-by-step instructions.
If you use the tool without prior knowledge, you might risk not being able to unlock at a later stage. You could take a look at the iPhone OS firmware update which we had written about some time ago, which was for iPhone OS v 3.1.2. The PwnageTool for iPhone OS v 3.1 was also covered and you might be interested in learning how to Jailbreak Your New iPhone 3GS.