Has been a while. The Apple Store is right now down for updating.
Apple changed the down for maintenance graphics. It has been a yellow post-it for years. Now a big grey box with the text: "We'll be Back." is greeting shoppers.
Today also marks the start of the Apple Store offering the NEST Thermostat. I am not sure if the Apple Store maintenance is related to that or if something else is coming today.
Via the Apple Store.