i have the iphone 4 4.1 (8B117)
i first downloaded the firmware - http://www.felixbruns.de/iPod/firmware/
then downloaded pwnage - http://www.iphoneworld.ca/news/2010/10/20/download-pwnage-tool-4-1-for-mac-os-x-iphone-ios-4-1-unlock/
i went on to expert mode on pwnage tool, clicked iphone...