GameSpy is working with Nintendo on middle ware tools for the Wii, when asked if Wii friends codes will be network-game specific GameSpy said "The answer to your question is yes, for the Wii friend lists are game specific."
Still, this isn't out of Nintendo's mouth, but it is coming from someone that will be supporting Nintendo in their online strategies. Who would know better than the person working on the online portion of the business model?
If we see Nintendo take this route we'll be doing a lot of extra work to game with friends. Perhaps Nintendo needs a numeric keypad accessory to ease the pain of Wii-code typing? It takes many of us hours just to connect with our friends (on this forum alone) - imagine having to do that action for every game you want to play?
source: 1up.com