Nintendo are going to be offering post-release content for New Super Mario Bros. 2. This was revealed during their Nintendo Direct video last night and has been met with mixed reaction by fans. Personally, so long as they can get the price right (something that I massively doubt), I don't see the problem in them offering more levels to people that really want them.
The levels on offer will be part of the Coin Rush mode, a mode in which you must finish three presumably difficult levels with only a single life. It's a nice idea and will manage, hopefully, to add a challenge for those people that finish the game quickly and without any problems.
Still, the anti-DLC brigade massively dislikes the decision and are claiming that Nintendo have crumbled to industry pressures. Pressures like "making money." Damn them.