Gamecube LAN titles will most definately *not* be supported.
AnyoneEB: I understand that for some people, the wired option is more viable. On the bright side, the Wii should have a far more robust handling of wireless networks - including the various serurity protocols. The Wii doesn't have the same constraints as the DS has.
What urks me is the people who blindly complain about the lack of built in ethernet and then turn around and complain about the lack of HD. Wireless networking is expanding faster than the HD TV market! If your all for new technology, lose the wires!
One last note about the Nintendo WiFi adapter. **If** it's a 802.11b adapter, look for Nintendo to have a "HighSpeed" or "Max" or something like that version when Wii releases. Basically releasing a 802.11b/g adapter. If they do, remember that 802.11b is pleanty fast for gaming (assuming your in a reasonable proximity to the adapter) and that Wii would be able to take advantage of the full speed of the link. The DS artificially limits the speed to limit power consumption. My point, you don't have to upgrade... try it first.