My DS definitely has selective memory. He knows every Pokemon ever created, what world their from, how they evolve, what they evolve too etc. (for those of you not familiar, there are 100's of these) He never forgets anything related to math, ever! But ask him what the movie was about last night, and you get "I don't know". His level of passion defines his memory completely.
My DS is the SAME way! He can tell you everything and anything you ever wanted or didn't want to know about the Power Rangers, Monster Trucks or repeat lines from movies and songs he likes or tell you what he had to eat two weeks ago (I have no clue why, but he's always been driven by food), but let it be something he's totally not interested in, and it's the same "I don't know".