Virginia Phillips in the Pittsburgh Post-Gazette has a terrific article on Pork Shoulder, which she describes thusly:

It's cheap. It's fatty. It's ugly as a box of rocks. This part of the pig is insensitively known as the pork butt, and it deserves a better name.

I went to the meat counter of a gourmet grocery store last year and asked for a pork shoulder, because I was going to make some slow-cooked pork for use in tacos. The man behind the counter dismissed me with "We only have high-end cuts of meat here."

Sorry.

In the article, Phillips offers tips for slow cooking a pork shoulder at very low heat. She also offers up a couple of suggestions for what to do with the leftovers:

Pulled pork: There's nothing simpler than gently reheating leftover pork, shredded with a fork, in a good bottled barbecue sauce -- Bullseye and Bone-Suckin' Sauce are recommended. Pile on a bun with coleslaw.

Build a taco: On a soft flour tortilla, spread refried black beans, homemade or prepared, a generous spoonful of shredded pork, pickled purple onion or jalapenos, and some avocado slices. Roll up, heat gently in the microwave and serve with fresh tomato salsa.

The latter is similar to what I was trying to accomplish with the shoulder I attempted to purchase above. I ended up getting the meat at Food Lion.