Apparently the face lift of the online Apple stores has finally “upgraded” the Luxembourg one to a proper one. Front page is no longer reserved for “business clients”.
However, the expected link (http://www.apple.com/lu/) still sends you to the Belgian iTunes + iPod page So the address is still http://store.apple.com/Apple/WebObjects/luxstore?type=bizbelfrLU&qprm=82404. Note that the prices are lower than in the Belgian store (= difference in VAT). Very good!