Everytime we get this exact same question,someone wants to debounce 64 inputs and everytime we go through the same old routine and everytime I say why dont you use the dallas switch debouncers as they are designed to debounce multiple inputs with lots of esd protection and provide a interupt input everytime the switches change state.Someone else will post something about vertical counters and someone else will post something about what his granny thinks.You do not need dedicated processors or any other wierd and wonderfull scheme.
argh talk about flogging a dead horse.

I find it quite increadable that nobody has suggested this as a very cheap and simple soulution,and dont make me post some vhdl code which will do the same thing in a cpld cos i will do it if you force me to ;)