PwnageTool is the jailbreaking tool from iPhone dev team which works only on Mac, similar to Pwnagetool is the Sn0wbreeze from ih8snow for Windows users which lets you to jailbreak your iPhone and iPod Touch by creating custom firmware. The first version of Sn0wbreeze was capable of jailbreaking iPhone OS 3.1.2 on iPhone 3G, 3GS & iPod Touch 2G, 3G.
Now that iPhone OS 4.0 is expected to be announced at WWDC 2010, iH8sn0w is getting ready his jailbreaking tool sn0wbreeze to support iPhone OS 4.0 jailbreaking. The first teaser screenshot of upcoming sn0wbreeze 1.6 was posted on twitter accidentally.

Sn0wbreeze will support jailbreaking iPod Touch 4.0 os and iPhone OS 4.0 on iPhone 3G & iPhone 3GS. However there is no ETA of Sn0wbreeze 1.6 release is available yet but it should be any time after iPhone OS 4.0 announcement.
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