wearable computers have been around for ~25 of those 40 years, you could buy a watch with standard personal assistance features in the mid 80's
heck even when I was in grade school they had come down to simple LCD video games and calculators that some kids would wear to school and get in trouble for (later 80's)
http://arduino.cc/forum/index.php?action=unread;boards=2,3,4,5,67,6,7,8,9,10,11,66,12,13,15,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,86,87,89,1;ALL