On Thursday, Nintendo discussed a new shop feature, DSiWare on the DSi which is somewhat of an equivalent of WiiWare. However, this means that Wii points would not be the only currency available. Nintendo additionally revealed “Nintendo points” on the same day and many assumed that this meant Wii points would get renamed and points for DSWare and points on the Wii Shop Channel would mix together. This is not the case, though. While Nintendo is interested in renaming Wii point cards to “Nintendo PointsPrepaid Card” in Japan, both the Wii and DS shop features will use its own points system.
Basically, this means the points aren’t applied to one universal account. When you cash a Nintendo Points Prepaid Card on the DSi, those points will not be able to be used on the Wii (and vise-versa). There are DSi points and Wii points, both of which are seperate from each other.