Another security problem plaguing businesses everywhere is the proliferation of the USB thumb drive. No matter how securely you set your permissions on your file servers, no matter how finely tuned your document destruction capabilities are, and no matter what sort of internal controls you have on "eyes-only" documentation, a user can simply pop a thumb drive into any open USB port and copy data over, completely bypassing your physical security. These drives often contain very sensitive information that ideally should never leave the corporate campus, but they're just as often found on keychains that are lost, inside computer bags left unattended in an airport lounge, or in some equally dangerous location. The problem is significant enough that some business have taken to disabling USB ports by pouring hot glue into the actual ports. Effective, certainly, but also messy.
In Windows Server 2008, an administrator will have the ability to block all new device installs, including USB thumb drives, external hard drives, and other new devices. You can simply deploy a machine and allow no new devices to be installed. You'll also be able to set exceptions based on device class or device ID—for example, to allow keyboards and mice to be added, but nothing else. Or, you can allow specific device IDs, in case you've approved a certain brand of product to be installed, but no others. This is all configurable via Group Policy, and these policies are set at the computer level.