On URL: http://arduino.cc/en/Main/ArduinoBoardUno, the link behind "mapping between Arduino pins and ATmega328 ports" should point to URL: http://www.arduino.cc/en/Hacking/PinMapping168 instead of URL: http://www.arduino.cc/en/Hacking/PinMapping328 (which gives me an "Insufficient privileges to perform action." message).