I think this is a great idea. Some of my fondest experiences
when I was a young-and-budding programmer were challenges of
this sort. I remember two in-particular. One was a day-long
programming contest I participated in in highschool. At the beginning
of the contest we were given a game (in this case, it was
battleship-like) and we had 4 hours to design and code a program
to play it, then
after lunch our programs were pitted against each-other with
the best program winning. The other happened when I was
in college. Everyone in my class had to write a program to
solve a sliding-tile type puzzle. For grading all of our programs were
given the same input and benchmarked and the one that solved it fastest got the highest
grade.
My only concern is that a Perlmonks programming challenge
like this could really burn up a lot of my free time :)
posts where several monks post
responses, and then someone benchmarks them seem to be
popular. I think "write code to perform task X
the fastest" challenges would be great and much easier
to come up with "have program X and Y fight to the death"
in a strategy type game contents. The ideas could be based
on real problems.