Welcome to Player Attack!
Notch endorses piracy... as long as it's ingame. He's announced today that his new game 0x10c will include - and potentially encourage - code-stealing between players.
Because I want virtual piracy as a gameplay element, the EULA for 0x10c will say you surrender all claims to code you upload to the game.
In-game piracy is a crucial element of the upcoming space title, but Notch (who created Minecraft in his spare time) has made the clause part of the compulsory agreement for a reason: It will prevent gamers from suing each other in the real world.
That said, action against pirates in the virtual realm can take many forms:
If you get organized and set up your own government ingame, you can reinvent patents if you REALLY want to.
We've seen in-game piracy as a gameplay element in other games - most notably EVE Online, where stealing and backstabbing other characters is a part of daily life, but this sort of behaviour has had real-world consequences, including players being taken to court over fraud and money laundering charges.