iPhone 3G doesn't charge with FireWire (USB Only)

A little known (but much loved by me) feature of every iPod (except the Shuffle) and the original iPhone was that you could charge the phone using the FireWire port on your computer. Of course, it's been quite a while since you could transfer data over FireWire, but you could buy a cable that powered the iPod/iPhone via FireWire and exchanged data over USB. Why would you want to do this? Simple: for USB ports to be powered, a Mac must be on (not in sleep mode). This means you can't sleep your Mac and charge your iPhone. However, FireWire didn't have that same requirement, and Apple kept the FireWire ports hot even as long as your computer was plugged into the wall, regardless of sleep mode.