We can turn a screen on or off (Standby) using a script or through the System Manager but there is no property in the Player Manager to tell you the current state. We should be able to list this property status in the Player Manager, System Manager and query it through a script. This could be used to trigger events and reporting.
As more people start thinking about their carbon footprint, the ability to shut down screens (place on standby) will be more important to them.