I couldn't remember. I see no physical off switch on it, just the power button which goes red once it powers down. I remember the Wii also had no switch, but it had two modes, one where it the disc drive would light up and the other was a power down with just the yellow light. I just feel weird about yanking the plug while the console is technically "on", even while off.
With consoles like PS2 and PS3, you have a physical switch that completely powers off before pulling the plug, and as for the Xbox and 360, while they don't have a power switch, at least they appear to completely shut off once you hit power. So Nintendo is the weird one, there is no switch, but the console stays lit and can still do things while in "off" mode.