If you have power management enabled in steam VR you can set the system up to put the base stations to sleep when you close the system.
At the moment though there is no indication what so ever that the unit is actually going to sleep. It remains full lit and then just powers down.
I wonder if you can add to one of your next firmware options some sort of visual to indicate that it is powering down.
With all the LEDs in the unit you might even be able to do something fancy and give a visual 10 second count down.
The reason I ask is that the system is buggy and on several occasions you power down and come back to the room to find the powerstations all still running. If we had the visual indicator we would know that they are going to sleep else we know to just unplug them.
Thanks for the suggestion! I think it would be very helpful (I just unplug mine, but it would be nice to know if they were going into standby or not.) SteamVR is constantly being updated and improved by Valve, so I wouldn't be surprised if we saw this feature in a future release.