Nintendo's big man Reggie Fils-Aime just said this in their conference call:
In terms of voice chat... certainly our system has the capability for online voice chat, what it comes down to is finalising the peripheral... I would not be surprised to see that capability come to this system.
What this means is that there's a capability of adding voice chat to the Wii fairly easily by way of Bluetooth headsets (which you probably have loads). And if you think that he's just dork-teasing with his "would not be surprised", execs usually don't even get to that base unless they're actively in development of something. However, the chat will only be available for Wii games and not Virtual Console ones. No multiplayer chat in Double Dragon, unfortunately. [Kotaku]