There has just been big Mii Plaza update on the 3DS.
The biggest change that I can see is that now there is the option to buy 4 additional games.
I've only taken a look at one and if it is indicative of the others, they are pretty pricey at £4.49 each.
There is also an icon for an 'Exchange Booth', but it does nothing on my system.
It seems a bit of a strange move, both in creating new games and changing for games that are dependant upon hits to function given that Nintendo have acknowledged that many people in the west rarely get Streetpass hits in comparison to Japan.