Safely Remove Hardware? Does it turn off Power?

I've been trying to research for our Computer Club whether or not the "Safely
Remove Hardware" applet actually turns off the power to the device and if
does, does it wait for the device to be physically removed before returning
power to the port?

I've noted the light on my USB flash drive goes out after sending the remove
command which seems to support this. I've also seen reference to the D3
power state when this command is sent but I've seen different D3 states
referenced on hot-pluggable devices.

I sure will appreciate any and all input.
Thanks,
Jim