That is a really complex matter.
However much time was saved it's value for mankind, the value added depends on what the programmer does on the spare time he gained from the increase in productivity and what value does mankind puts in these activities.
(note that value for the world as stated in the question is a lot harder to grasp)
At the end of the day it's a matter of knowing whether the programmer was the bottleneck of the productive system he is a part of or if he had slack capability.
EDIT: I was going to post a more complete answer, with references bells and whistles, on Stack Overflow, but having never created an account there I didn't have the 10 reps minimum. Kind of dumb for a question with zero answers IMHO.
(note that value for the world as stated in the question is a lot harder to grasp)
At the end of the day it's a matter of knowing whether the programmer was the bottleneck of the productive system he is a part of or if he had slack capability.
EDIT: I was going to post a more complete answer, with references bells and whistles, on Stack Overflow, but having never created an account there I didn't have the 10 reps minimum. Kind of dumb for a question with zero answers IMHO.