Anyways, Nintendo has really let us down....
I play XBox Live daily, and they have a system that is perfect. You have a friends list that is universal for every game. You are identified by a gamertag. You can have up to 250 friends and can choose which ones to invite or which game you want to join.
There are also Matchmaking options that match you with players of your rank or skill level.
It's perfect, and in Halo 2, they even allow you to sign in a guest that can play games and even go on to certain matchmaking playlists.
In short, Nintendo screwed up.