Apparently, a trusted person at the IGN Insider forums, who has been right before about a speaker in the Wii controller, has dropped a few pieces of information.
“…voice communication will be via wireless, head-mounted microphones…”
“Some peripherals for the DS will be compatible with Wii and vice-versa.”
“Many Nintendo first party games (specifically games designed for a younger audience) will feature a new system currently being developed by Nintendo called ‘voice to text communication’.”
“The system works using an advanced voice recognition system which Nintendo has been developing for several years. When a user speaks the sound is converted into on screen text and sent to the other players. However, rather than just plain text being sent the system also picks up the tone, pitch and volume of the voice and translates that into colour, font size and character set. For example, if a player shouts ‘I win’ loudly into the microphone the on screen text may be all capitalized, and in a large red font; conversely if a player speaks quietly the font may be a pastel shade and smaller.”
This system also allows online voice communication to be easily censored by the user.”