I agree that this is easiest, and I'm surprised that the article calls it "hardcore" (slides 38-39). But it does bring to mind a more devious challenge: Someone ran "chmod -x ld.so"...
find / -type f -perm +x | xargs chmod -x
EDIT: chmod has to be the last program to be chmodded, in the above list.. :-)GNU Parallel http://www.gnu.org/software/parallel/ does not have that problem.
Watch the intro video for GNU Parallel: http://www.youtube.com/watch?v=OpaiGYxkSuQ