It has been mentioned (and forgotten again) before that the wedge works really well against holes in the enemies formation. The problem with wedge is that though it gives a powerful +3 attack and a push-back bonus, it gives -3 defence making the unit very deadly and very vulnerable at the same time. I never use wedge, but I understand that is is very maneuverable and cannot be flanked. It is not faster than close formation (at least not when I checked it in S:TW) but it can turn more easily. For me, units in wedge die too fast to make it worthwhile. If I want to exploit a chink in the enemy formation I use a column.

BTW, the tactic you mentioned as being invented by Napoleon was already used by Alexander the Great at Gaugemela. Nothing's new .