The lead in to Mythbusters, Anatomy of a Shark Bite, was pretty gruesome (at least the ending). It's about one of the only shark bites on a human caught on tape and then the victim trying to recreate the event a year later to see exactly how a shark bite works.
I believe that entire episode was an exact re-run from last year, for some reason. Bummer. I wish they'd show the other clip where the girl gets munched by a Great White with cameras rolling during her Senior High School trip I think (shark stays under water the whole time so you can't really see it). She "only" lost her leg, but it was a pretty good battle, with folks screaming at her to watch out, and trying to help her and pull her away from the shark. No idea why they haven't exploited that cool footage on Shark Week yet (happened about 3 years ago now).
As for Mythbusters, eh, that was kinda lame. They just went through the whole Jaws movie and tried to recreate the stuff from it to see if they could really happen that way in the real world (shark towing a boat, shark ramming a hole in the boat, blowing up a shark with the oxygen tank, etc.)