Well, any
competant iBook user should know that if you look between the
F4 and
F5/
Num lock keys there is a small notch. Actually it's a transparent
screw over the
Num lock LED. Turn it clockwise to lock the keyboard. Great for schools.
Anyway, it's still hard to steal RAM, it is covered by a plate requiring the removal of 3 screws, not to mention the optional airport card on top of it.
Powerbooks have the same, though it's between the F5 and F6 keys.