Unmount USB devices

I don't belive it's a bug.

The same issue applies with PC Card storage where they are still powered after they are have been unmounted. If you look at the menu bar you will notice a PC Card icon on the right side. There is a "Power off card" item in there and if you select it your light will go off. In most cases you will find that the light on your card will signify power rather than access (access is indicated by the light flashing).

I always power off before physically eject my PC Cards. While I don't belive it matters either way it's always best to be safe than sorry.

Is it not just to drag the device I wish to unmount to the trashcan or press "unmount device"?

If you are referring to a USB hard drive then yes, all you need to do is to drag it to the trash to unmount it. Just remember that unmounting a drive/device does not power the device down. It just unmounts it. As long as the drive icon disappears from desktop (assuming you are showing drive icons on your desktop - if not you need some other means of determining the drive's mount status) the drive is unmounted and can be disconnected from your PowerBook and hence, power.

Are you referring to a ejecting USB card adapter device? I've noticed that with Tiger (10.4) my Lexar card reader doesn't switch off its access light when I eject the card. Another Tiger USB bug, I guess.