The Wii uses WiFi technology. If you don't know what that is, then go to howstuffworks.com/wifi (or something like that). Anyway, the Wii will use a program called the "Opera Web Browser". It allows you to connect to the Web via Wii. When you suscribe to Opera, you will get the first six months Opera Web service for free. After the six month trial, you can either unsuscribe, or pay $99 (U.S.) to buy it.
But where is where the offer really gets good: once you pay the first $99 fee, the Opera web service isfree. That's right. There is no by monthly service charges. One payment, and that's it.
*Note* I think that Nintendo uses their own internet to link Wii's together.