I think it's possible for the DS to be able to play against anyone in the US, but it's probably not going to happen anytime soon. The DS has WiFi capabilties, which lets it network with other DS units in a certain range (I don't know what that range is). Theoretically, you could bounce a signal across multiple DS units and relay that signal to a certain destination. Of course, that would depend on how many DSs are around to act as a hub... and then it gets all complicated and stuff. So as of now, you'll have to make do with wireless networking capabilities with other people who are near you.