Lisa,
I believe that you purchased an Iomega 250 GB FW/USB HD. I think I have the same or similar drive. I have an Iomega 250 GB Black Series Triple Interface HD.
The power management of this drive is a little different than you might expect and it has nothing to do with the cloning process. I have confirmed the working of this with Iomega and they assure me that it is a feature and not a bug.
The Iomega that I have cannot be powered off while connected to the Mac with Firewire. The power coming from the Mac through the FW cable keeps the blue power light on on the Iomega. If you want to power the Iomega off completely, you must first unmount the drive from the desktop (always do this before disconnecting the FW cable), then disconnect the FW cable, and then depress the power button on the Iomega (or unplug the power cord). I just depress the power button and leave the power cord plugged in. That way, the next time I use the Iomega, I just plug the FW cable into the Mac and the Iomega spins up.
I think this is a strange way of handling power on and off for the Iomega drive. As I've stated, I went through a very long series of emails and phone calls with Iomega last winter and they were unwavering in saying that this is the way it is supposed to work.
Let me know.
Regards,
Steve M.