[Original Link] Here’s a hint I found quite useful. On the Powerbook, the function keys, by default, do other things like changing the brightness of the display or turning numlock on and off. To make them operate as function keys, you have to press ‘fn’ at the same time. If, like me, you use them more as function keys (for exposé etc), you can invert this behaviour in the Keyboard section of System Preferences.
Function keys on Powerbooks
October 21st, 2004