For anyone with this equipment you must enter your connection information manually as the wii connection will fail. For an Airport Extreme Base Station Enter the Folliwing in your Wii online settings:
WEP/WPA Key: whatever it is, if any,
IP Address: 10.0.1.15
Router Address: 10.0.1.1
Both DNS Servers: 10.0.1.1
And you're done. If you enabled MAC address filtering in the router you will need to also add the Wii's MAC address to your allowable connections.
For those of you trying to use your shared Airport connection from an actual macbook, ibook, iMac, etc. The same as above must be done except setting the computer to a static IP address and changing the Router and DNS server addresses above to match. Set the IP address of the wii to whatever your router address is +20: eg. If your static IP address is 192.168.2.10, set the Wii's to 192.168.2.30
And that's it!