highly doubt as much as you want, but this is straight from Mike's site
The 580EX II has a MANUAL mode and an AUTO mode. The AUTO mode is often just referred to as the eTTL mode. This is pretty obvious, and this are the two ways the flash will operate in. Now, this flash has a wireless controller system (whcih is separate from the MANUAL or AUTO modes of operation) that operates in the IR (infrared) spectrum which is generally line of sight, or slight bouncing of the rays, just like your television remote control. The PW's operate in the RF (radiofrequency) spectrum, and these waves travel much further, and through many obstacles. This wireless controller can be in one of 3 states of operation: OFF, MASTER, and SLAVE. If you have 3 states of operation of the wireless controller, in each of the 2 modes of operation (MANUAL or AUTO), this will give you 6 separate operating modes. The PC Jack as it is wired from the factory, is NOT active when the flash is in the MANUAL-MASTER mode of operation. The Re-Wire Mod will make this PC jack operational in this specific mode, which is used when the 580EX II is used off camera and connected to a PW (receiver) which is being triggered by a PW (transmitter) in the camera hot shoe. If this is the extent of your setup, then the 580EX II can be set in the MANUAL mode with the wireless component in the OFF position, and all will work fine. If you are wnating this 580EX II flash to act as a MASTER flash to trigger another flash unit which is set as a SLAVE unit, then you see that this 580EX II unit would need to be in the MANUAL-MASTER mode, which turns the wireless controller ON while in the MANUAL mode of operation. Just above (in this paragraph) I said that the PC jack is NOT active as it comes from the factory when the flash is in the MANUAL-MASTER mode...unless the Re-Wire Mod is done.
So, yes indeed you can re-wire the 580exii to be set into manual master mode and fire off slaves in a group.
Don't mess with me when it comes to off camera speedlights, I am a God.
Oh, and in case you were wondering, the stock 580ex does not have the pc terminal disabled in manual-master mode, as the stock 580ex does not have a pc sync. I believe you may have the 580ex confused with the newer 580exii