Apple Locked Digitally Signed For iOS 4.0.1/3.2.1

A few hours ago Apple has blocked the digital signature for the firmware 4.0.1 and 3.2.1 , so now it is impossible to restore to an earlier iOS version. From now users can't save SHSH files to Cydia or Apple for iOS 4.0.1 and 3.2.1 or lower.
so those who upgrade to firmware 4.0.2 will no longer able to restore or unlock their iPhones, in addition who upgrade his iPad to 3.2.1 will no longer able to unlock his iPad.

But for those who have already saved SHSH files as we mentioned before, they will have no problem see guide posted here.

I highly recommend to all those who have not saved SHSH and want a jailbroken device, don't upgrade to iOS 3.2.2 for iPad users (iOS 3.2.1 already jailbroken here) and if you are an iPhone  user don't upgrade to iOS 4.0.2 (iOS 4.0.1 already jailbroken here).
For iPhone 3G users, it is already jailbroken on iOS 4.0.2 using reds0w here.