According to these Wiki Details:
Quote: "One criticism of the Wi-Fi USB Connector is that it uses a proprietary authentication mechanism. Because of this, the Wi-Fi USB Connector works only with approved devices, which at this time is limited to the DS and Wii consoles.[5] This behavior was an intentional design decision on the part of Nintendo, as it prevents outside parties from connecting to the Wi-Fi USB Connector with their computers and accessing the user's Internet connection or computer. Still, many users would appreciate the option of using the Wi-Fi USB Connector with standard wireless devices.
While the Wi-Fi USB Connector can be modified to circumvent this,[3] the modification is beyond the capability of most users and is naturally unsupported by Nintendo."