The company I just started with has been using this technology for a while now. Cisco is about the only company that really has this figured out. For instance not sending voltage down a wire to a device that isn't set up for it.
Another cool device is the KVM over IP, which is essentially a KVM that runs over an ethernet cable. We use alot of these too so we don't have 3 cables for each machine in a rack, just one goes to the KVM for keyboard mouse and monitor.