I ran this jailbreak on my wife's 4.2.1 iPad the other night. All I did was plug the iPad into the computer, turn it off, I don't even have iTunes installed on the machine I did this on, and then launch the app. It has you boot the iPad into DFU and then it runs the jailbreak. Then you launch the new app on your springboard to install Cydia and you are all set. It really doesn't get any easier than this. No need to backup anything unless you plan on restoring it in the event you want to go back to normal. The way I figure it, if I decide to go back to unjailbreak, then I am probably going to want a clean restore on the device and not something already linked to my account, so I didn't bother with a backup. All the apps I downloaded from the app store were still there, so this jailbreak is really non-intrusive and safe. I know it is a little stressful to start tweaking your several hundred dollar device, but this is really an easy and safe process.
