Nintendo has released a DS branded Headset intended to be used with the two newest DS Pokémon games. The mostly white headset plugs into the Headset Connector port at the base of either the DS or the DS Lite. This allows the user to hear audio and speak into the microphone for certain games or, through either Pokémon Pearl or Pokémon Diamond, use the voice chat feature to talk to other online gamers.
Nintendo slyly slipped in mention of the Headset toward the end of the Pokémon Diamond/Pearl press release without indicating a price or release date. According to a few online sales sites, the DS Headset is currently available for $9.99 and appears to only be available in white.
Look for a review to be posted soon. Initial comments so far - seems to work well enough but the microphone is a little short for an average adult size head.