One of the biggest changes I've observed as an old time gamer (AD&D 1st ed, Shadowrun 1st ed etc) versus now exploring 4th ed D&D (and reading about 3.0/3.5 and d20 systems etc) is that now people talk in terms of "Strikers, Controllers, Leaders and Defenders" and categorize most characters into one of these roles (and the DMG itself suggests a party should have at least one of each role.
This is a very big change from how we played back "in the day".
I'm curious when and how this entered into the gaming lexicon? I thought I heard it comes from MMO's and computer RPG's - is that the case? (and if so does anyone know the full history)?