Nintendo points not transferable between Wii and DSi
One card but two types of points

The confusion over whether Nintendo Points (previously Wii Points, now renamed so they can be spent in the DSi Shop too) will be transferable between the two consoles has been cleared up.
They're not transferable. When you buy them you'll have to decide whether you'll be spending them on DSi or Wii.
The news - reported by Siliconera - means that although you'll have one Nintendo Points card, the points on them will be fixed to one console.
It was perhaps predictable since Nintendo doesn't have a centralised account system to control the digital distribution on both consoles. But we'd kind of hoped it might be able to do something to make the process a little slicker. Obviously it wasn't to be.