As an example, my Moto RAZR has a mini-USB for power, so I figured I could charge it from my computer. Well, I could, but it required a special driver to set it in a power-supply mode. I had to go out and find the driver, then install it. For me, no problem. For someone who doesn't want to muck with this, could be a bigger deal. Of course, I don't know what would happen on a Mac if one plugged a RAZR into a USB port and it didn't have the power supply driver.
That's easy. It won't charge on a mac either without a driver, if you can find one for it. This is the Razr, not the PC, because they are doing something non-standard with usb power. Yeah, I have a Razr also, so I know what you are talking about w.r.t. needing the driver so it will charge when plugged into a standard usb computer port.
This really has nothing to do with this topic.
Anyway, if you have a mac, you're supposed to have an iphone. hahaha. (in addition to your collection of ipods, apple tv, airports, airport express, apple time machine, .mac subscription, etc, etc.)
-David