In theory powered USB sockets (maybe USB2 and later) can control the power if the hardware supports it.
I don't know if my H/W supports this function, but that's a mute point as I've never found any S/W that implements such control. Has Windows7 made any advance over XP in this arena?
This issue comes up once a year, at about this time, as I have USB powered desk Christmas Tree. OK, it has a switch on the bottom, but I'd really like to be able to control it with an application if possible.
The tree sits on my windowsill, and it's not easy to reach over my monitors. And yes, if this is the worst of my problems, I'm obviously doing OK.