If you are one of those users who prefer to download iPhone updates with your favorite download manager , then here are the direct download links to the iPhone OS 4.0.1 update for the following devices -iPhone 4 , iPhone 3GS and iPhone 3G. If you are using a jailbroken or unlocked iPhone do wait for a few more hours before going ahead with the update while we confirm if it works.
iPhone 4 [579 MB]
iPhone 3GS [378 MB]
iPhone 3G [305 MB]
After download the .ipsw firmware file , open iTunes 9.2 on your PC and do a Shift+restore with the file. If you are on a Mac you need to do a option+Restore and pick the file.