at the moment i think you can only use your friends to send messages and for mii travelling, but if it's anything like the DS when the on-line multiplayer games come out you will be able to play different types of games with friends than you otherwise could with non friends.
i'm really hoping that they don't limit on-line play to friends only!!
You can send 'em pictures as well. And I would assume you could send video clips as well, but I could be mistaken because I've not tried it. Not that I have a good reason not to. I'm going to try it right now. I'll let you know when I get home.
