Dev team has released iPad 4.3.1 jailbreak for the iPad. This jailbreak guide is compatible with iPad running iOS 4.3.1 firmware. This iPad jailbreak guide works for both Windows and Mac.
UPDATE – If you have upgraded to iOS 4.3.3, make sure to check out the iPad 4.3.3 Redsnow jailbreak guide.
First, you will have to download 4.3.1 firmware for your iPad (link given below) and update your device using iTunes 10.2.1. Then, download Redsnow for iPad and start the app. Browse for the iOS 4.3.1 file.
Click on next and select “install cydia”. Here, you may select any other option that you may like.
Now, you will need to turn off your iPad and then plug it in into the computer before you press the “next” button.
Now, you will be asked to put your iPad into DFU mode. Doing that is simple – hold the power button for 1 second and then while holding it, press the home button as well. Then, after few seconds, while holding the home button, release the power button. Installation should begin now.
That is it. Wait for sometime while the Redsnow does the magic.
Note – iPad 4.3.1 PwnageTool instructions are here, which is an alternative method of achieving same results.