Dripwn
Dripwn simply extracts the Zephyr files from ANY device plugged into your Mac.
Dripwn 1.x is a simple, open source, tool to simplify extracting the Zephyr firmware files from Apple restore IPSWs.
Dripwn 2.0 however, simply extracts the Zephyr files from ANY device plugged into your Mac. It is a MUCH better piece of software, once again, developed by Munnerz and released on 04/05/2010
There is also a command line utility that can be checked out from the repo below that can be run and compiled for Win32/Unix. It can be found as part of the xpwn source.