CVG reports that one of the accessories you'll be able to purchase for your Wii later this year will be a wired ethernet kit, presumably a device that automagically enables you to connect your console to the interwebs via an antiquated cable. Like the high-end model PS3, the Wii features Wi-Fi capabilities without the need for an additional adapter, though it seems decidedly odd for an online system to ship without a standard ethernet port.
Nintendo has long made a big deal about embracing all-inclusive standards (which exclude HDTVs) and getting everyone in on the game -- making users pay extra in order to utilize a standard wired connection (which most wireless routers also support) seems contrary to that. It's a strange sort of reversal of the option found in the Xbox 360, where the wireless adapter is purchased seperately and the ethernet port is already included. A further option can be found in Nintendo's USB Wi-Fi dongle, as it's been confirmed to work with the Wii as well.