While Nintendo seems pretty insistent at not porting their games over onto mobile devices like smartphones and tablets, it would appear as though they are considering an app store of their own for their upcoming Wii U which will be similar to that of iTunes or the Android Market. A recent rumor seems to suggest that non-game apps such as MLB.tv will be allowed to run on the regular TV interface, along with more tablet-like apps that will be optimized for the Wii U's 6.2" touchscreen display. According to the rumor, the new app store for the Wii U will have a "wider variety" than that of the DSiWare and WiiWare currently offer.
Ubergizmo, Nintendo Wii U might be getting an app store of its own