Why do new videogames take so much room to save?

I'm just wondering why new video games take so much more space to save than old ones? For example a Playstation 2 game takes about 150 kilobytes to save but a playstation 3 game takes 150 mega-bites to save. I could understand if new game took a little more room than older games to save but a 1,000 times as much?! Why do new games take so much more room to save, what the heck are they saving?!?