Pork brisket is simply a substantial part of a boned-out picnic ham. (A picnic ham, as we discussed in a Nasty Bits post regarding the primals, is the lower half of a full shoulder on a pig.) I'm calling this cut on the pig a pork brisket to emphasize that what we value on the beef brisket—the fatty marbling and connective tissue that breaks down with cooking—can be found on the the pig as well.
Though it's sometimes dismissed as too fatty, a pork brisket is actually an ideal cut to roast or braise. Roasts, whether dry-roasted or braised, can be tricky to get just right. Unlike soup bones, which can be cooked for as long as you like, or steaks, which are generally better on the undercooked side, a roast must be perfectly tender and juicy to be good at all. A well-crafted jus can mask some of the problems with an overcooked or overly lean roast, but there's really no hiding a large hunk of meat that's too dry to be palatable.