Thanks for the replies so far, but also I forgot one other question...

>>What is the pin doing in input mode? Is it high impedance or something? Is
>>there any electrical difference between the pin being in input mode or the
>>pin being in ouput mode with a '0' in the SFR?
>>
>
>actual output state. So, a pin in input mode "looks" electrically like a
>capacitor of about 10pF or so.

[this is bad one...]
Does this mean that in effect there is no (or very very little) current flow
into the pin in input mode? If for example I stuffed that LED and resistor
connected between supply and the pin, then set the pin to input, I take it
the LED would not light?

Kind Regards
Catchy...