Well it is my conjecture seeing these three things that each game that supports it will give you some short of trinkets for the various accomplishments in the game. For example: Sport Connection trophies look a little like Heismans and the ones in the Rabbids look like gold cups with a R forged in them.
And you can pick and choose which ones you want to display in the MiiVerse, much like the trophy system on the PS3, and they will be handled in the simular way to what the Mii's do on the 3DS greet the person say something about them and show their accomplishments.