John Gruber of Daring Fireball reports that Mac apps whose developers didn't follow Apple's advice on validating apps (link for registered Apple developers) can easily be copied by users. Gruber notes if Mac App Store developers are following Apple's advice, the technique for using a copied app won't work, but many apps aren't following that advice. He suggests Apple test for this in their review process and reject apps that are vulnerable.
Sean Christmann explains on his blog, CraftyMind, how developers can better protect themselves against copy
