Well CLEARLY if it was the greatest technological advancement of the millennium it'd also be the greatest of the century as well! 
"Misdirection? What ME?!?" >POP!< "Or ... ME?" >Poof!<
lol maybe so if the printing press was invented in the 20th century, but not sure Edison. I did not see a show for the 20th century though. I would have to say the assembly line invented by Ford in the early part of the century which ushered in the industrialized society, though I am sure some would argue for refrigeration.
