In case you’ve been trying to connect to iTunes and getting errors due to high demand wishing to update to the new iPhone 3.0 OS, try your luck with downloading the .ispw directly from Apple below. Make sure you download the correct version & then when your iPhone is connected in iTunes hold down the “OPTION” key and click restore. Browse for the .ispw file and go at it.

iPhone1,1 (iPhone Original)

iPhone1,2 (iPhone 3G)

iPhone2,1 (iPhone 3G S)