Those of you who need to jailbreak one of the latest generation iDevices like iPhone 4 or iPod Touch 4G would have to be running a tethered jailbreak solution (the untethered version is still under testing). The iPhone Dev team have just added a bit of sophistication to this tool by introducing a one-click support to the software. Using this latest version, you may bypass the several screens that one may come across while tethered booting.
The one-click jailbreak tool offers a few command line arguments that can perform tasks such as
-j to ask redsn0w to “Just boot now”
-i <filename> to specify your reference IPSW
-o for old-bootrom iPod touch 2G and iPhone 3GS
-b <filename> to specify your own boot logo png