Version 6.1.0-12U available via wireless Internet connection includes the following improvements:
Changes to StreetPass Mii Plaza:

The option to update StreetPass Mii Plaza is now available from the Streetpass Mii Plaza menu
Updating StreetPass Mii Plaza will provide new features, such as the ability to change your Mii character's expression and the ability to purchase new StreetPass Mii Plaza games*
*The ability to update within StreetPass Mii Plaza and purchase paid content is only available to users in regions where the full version of the Nintendo eShop is available.

Improved system stability and usability:

Further improvements to overall system stability and other minor adjustments have been made to enhance the user experience