Steps To Downgrade iOS 4.0.2 to 4.0.1 for iPhone 4, 3GS Without Saving SHSH Blobs
If you have a new iPhone 4 or iPhone 3GS on iOS 4.0.2 you can downgrade it to iOS 4.0.1 without saving SHSH blobs which will allow you to jailbreak and unlock your new iPhone with JailbreakMe.