If by "official software" you mean actually publishing a piece of software to the eShop, no. Nintendo has strict policies about the use of the SDK and those licensed to use it and the knowledge that goes with it. The SDK also does not contain the means to enable code to run on retail devices. However, there's nothing stopping you from becoming an official developer through their application process at
http://warioworld.com.
Otherwise, if you're interested in developing homebrew, there's technically nothing that you can do with the official SDK that can't be done with devkitARM & ctrulib (which you are encouraged to use because they are both free, as in freedom, and open source).