For those who has upgraded their iPad software to iOS 4.2 and wants to jailbreak the device, I recommend waiting until there is a untethered jailbreak. There are some tethered jailbreaks that will work but you will have to plug in your iPad every time you boot it to run your jailbreak apps.
There are no advantages to a tethered jailbreak, a tethered jailbreak means that each time your device loses battery power or needs to be rebooted, you must attach it to a PC or Mac to boot into the jailbroken state. Unless you’re in a huge hurry to jailbreak, you’re probably better off waiting.
Normally, I don’t recommend users with jailbroken devices to upgrade their software until there is a untethered jailbreak released for the new software. Since iOS 4.2 has so many new features and since iPad users don’t require a unlock, it makes sense for most iPad users to upgrade to iOS 4.2.
The draw back is you are left waiting for a untethered jailbreak that will work with iOS 4.2.1.
We will keep you posted.