Notch seems to be adopting Google's 10% time (to some extent), but rather with 50% time.

   "Because I want to avoid us just focusing on reaching release,
   I suggested that we should dedicate 50% of the development time
   in Minecraft towards adding fun new stuff. Basically, any developer
   working on the game (two people at the moment) can just come up with
   something they’d want to add on a day-to-day basis, as long as the
   rest of the team thinks it’s a decent idea. If it ends up being fun,
   it gets added." [1]

Sure, that 50% time will still be spent working on Minecraft. But it won't be the same as the other 50% time when the developers are trying to reach deadlines and so forth. I think that Notch is now taking control of how the company functions, which is a good thing. Before, it was just him and there was nothing but meeting deadlines. Now that he has more people to help him, he can focus on fun things like this.

[1] - http://notch.tumblr.com/post/2687176736/information-dump-inc...