I’ve been enjoying using my ipod touch at home to play words with friends. I get the wifi from my mac, using it as a hotspot at home. The trick is in the System Preferences for Internet Sharing.
snow leopard refers to airport, lion calls it wifi: http://osxdaily.com/2012/01/05/enable-internet-sharing-mac-os-x/
My MBP with snow leopard didn’t have any issues. On a different machine running lion I had to change the channel from 11 to 9 when setting the password to get it to work. apparently lion has some wifi issues? anyway, that was a quick fix.