Already a few people asked me how to configure Wifi properly under debian using
the /etc/network/interfaces file.
It’s not yet documented in the manual page of the file, but it is documented in the file/usr/share/doc/wpasupplicant/README.modes.gz
An example setup for wpa2:\
auto ath0
iface ath0 inet dhcp
wpa-driver madwifi
wpa-ssid fredsnet
wpa-passphrase fred was here
wpa-key-mgmt WPA-PSK
wpa-pairwise TKIP CCMP
wpa-group TKIP CCMP
wpa-proto WPA RSN