I ran into a bit of an issue trying to connect a suite of Gumstix computers to my local Airport Extreme (WPA2) WAP. The fix is really simple; I just had to add a “proto” configuration in the /etc/wpa_supplicant.conf file:

network={
        ssid="yourSSID"
        proto=WPA2
        #psk="your_passphrase"
        psk=bf83f4c896110b115bee8ff77b372f844435108950476a51667dd1b4a97e5b98
}

The rest of the directions here are still good.