Speaking of M&L:BIS, I've been reading about stuff since the ROM was dumped early (thank the people working at game stores who can't stop fellow employees from doing things like this when shipments arrive - the same thing happened with Pokémon HeartGold/SoulSilver), and it sounds like the game has some great copy-protection. From what I understand, it checks at the file selection screen (so people wishing to get around this can't perform an ARM7 file transplant, because the game creates a save file properly) and then a second time during the first battle (thwarting the first patch). Unless something's changed, the US version of the game only works on a handful of cards that an approximate total of seventeen people on Earth own.
I hope there are more checks later on in the game, perhaps one at every boss fight. This is the kind of thing that, if iterated enough, could cause people to give up in frustration and go buy a copy of the game. It's just too bad that most games don't have anything close to this (to compare it to some high-profile games that were uploaded to one particular site on the same day, there's no copy-protection at all in HG/SS or Scribblenauts).