The wall flush-buttons are common here in Norway as well - at least in public or office toilets. They usually (but not always) have a choice of a big or little flush.
Do you mean wall as in the flush button is part of the wall above the toilet, or wall as in the flush button is on a remote completely separate (often on the side or in front of) the toilet?
Because the latter is what you get in Japan, see what patio11 posted above.
It is definitely built into the wall instead of a sort of unit. For reference, the little stainless steel panel above this toilet are the flushing buttons, the sizes representing the amount of flush you give.
Yeah that's a fairly standard "integrated" toilet (where the flushing system is hidden into the wall), it's really quite different than the experience you get in japan.
