A quick howto for all of you that need to change your WIFI mac address (run this from root user):
#!/bin/bash
hexchars="0123456789ABCDEF"
end=$( for i in {1..10} ; do echo -n ${hexchars:$(( $RANDOM % 16 )):1} ; done | sed -e 's/\(..\)/:\1/g' )
MAC=00$end
service network-manager stop
ifconfig wlan0 down
ifconfig wlan0 hw ether $MAC
ifconfig wlan0 up
service network-manager start
echo $MAC