I always thought a cracker (beyond the food and ethnic slur definitions) was someone who removed copy protection from software. So, in WarGames, David would have been considered a hacker, but the guys you see in the splash screens of shared old computer games were crackers. Even if that isn't the formal definition, my guess is that is the most common connotation associated with that definition of cracker.

Make that never. 'Cracker' sounds stupid and already has racist connotations. Personally, I'd like to call people who illegally subvert computers for financial gain or ego-tripping, 'criminals' and be done with it.