Comex recently released the code for Spirit to run on Linux, and in doing so released bits and pieces of the source code. http://github.com/posixninja/spirit-linux/blob/master/igor/map.plist Posted here is the codes that it uses to jailbreak the device using the dylib from the firmware. Basically, this is what checks if you're on 3.1.3 or 3.1.2 and allows spirit to jailbreak your device. Technically, if we were to add this line in, we could jailbreak any 4.0 beta. (This is an example for an iPod Touch 3g) <key>iPod3,1_4.0</key> <string>igor/f6c17e934ba0ad477812de0b7cb019396d259d93.dylib</string> (I think this might be the correct dylib for 4.0 for iPod Touch 3g, but I'm not entirely sure) So, if we can find out the filecode for the dylib (I would do it right now, but not being near my Mac at work to go on 4.0 beta, and not being near linux to run this) we could jailbreak 4.0 betas. Please keep discussion relevant.