Nintendo really delivers the mature titles in more ways than one. If you want blood and gore, it has the 3 goriest most ultraviolent games to EVER grace gaming consoles, and they're all exclusives. Where else could you get:
Manhunt 2
MadWorld
No More Heroes
and pretty soon,
No More Heroes: Desperate Struggle
Those 4 games alone have more blood and cold-blooded murders than the entire PS3 library.
But if you also want really really mature games, you have Brain Training and Big Brain Academy, and board games and card games and other boring mature folks stuff.
Sony and MS seem to be fighting over the kiddie market with LBP and Viva Pinata. Well, good luck to them. They can have it.