I am curious about this because it uses the internet sharing option which is forbidden and could terminate your ISP. But it uses WLAN from you Airport to broadcast the signal thru your Powerbook/iBook/MB/MPB/MP/iMac. The guide is from here but I want to make sure it's safe before I use this option instead of wireless router.
http://guides.macrumors.com/Connecting_Mac_with_Wii
http://guides.macrumors.com/Connecting_Mac_with_Wii