http://www.nintendo.com/overviewds
Wireless Network
You can connect with a local wireless network of up to 16 players.The wireless range can be an incredible 30 to 100 feet and for some games, multiplayer requires just one Nintendo DS game card.
Future games may take advantage of the DS Wireless LAN connection for more multiplayer possibilities.
Note: Nintendo DS wireless communication, including PictoChat, is not private and is not monitored by Nintendo. We recommend that you never reveal any personal information or arrange to meet a stranger.
Microphone Port
A built-in microphone port means that with Nintendo DS, you only need to tell your games what to do.
Developers could create games which identify everything from voice commands to hand-clapping. Imagine moving your characters simply by telling them which way to go! Communication-based games could use the microphone and you can chat with others over a local network, or even the Internet in the future.
The Nintendo DS microphone gives you even more ways to interact with your favorite games.