Wallstreets do flicker the light and make popping sounds from the speaker when you plug in the power adapter normally I think. This happens when the PRAM battery is flat. The fan should also spin for a second or so if you listen closely.

There is a little diagram next to the ports on the back that tells you the key combination to reset the PMU. I believe it's fn+ctrl+shift+power. I could be wrong, but I believe you must use the key combination because there's no actual button for it. Lombards and Pismos do have the little hidden button though.