Out of curiosity, I did a Find scan through my copy of the 3.5 PHB. It never once uses the words 'memorize' or 'forget' in relation to wizards and spells, but exclusively refers to it as 'preparing'. For that matter, it also specifically elaborates on how the 'preparation' process in the morning is casting almost all of a spell minus the last few trigger words.

Anyone have a copy of the 4E or 5E PHBs they can poke into and check for the same?