Bluera1n is a software tool which can jailbreak (not unlock) all iPhones (iPhone (Edge), iPhone 4 iPhone 3G and iPhone 3GS) and iPod touches (iPod touch 2G and 3G MC NON-MC) running on the firmware version 4.0.2
IMPORTANT: Make sure that you have your SHSH files saved. You can jailbreak without saving SHSH files but you wont be safe once Apple patches the exploit used by bluera1n. Follow the instructions posted here to save your SHSH blobs.
The following step by step guide will help you jailbreak your device on iOS 4.0.2.
Step 1: Download and install the CUSTOMIZED version of iTunes (download link given below).
Step 2: You will need to be on the official iOS 4.0.2 (or iPhone 3.2) for iPad.
Step 3: Download bluera1n.
Step 4: Click on Jailbreak:
Step 5: Let the app do its thing and wait for the app to show Jailbreak Complete! message. At this point, wait for the iPad to automatically reboot.
Step 6: Voila! You should now have a fully jailbroken iPhone iPad on iPad iOS 4.0.2. Cydia should be there in the list of applications on your iPad