The 3-2-1 method is actually 3 hours in smoke, 2 sprayed and wrapped in foil and back in the smoker, 1 still wrapped in foil and in a cooler.
Oh Poopers! John is right on. My hands were faster then my brain was. Thanks for the save, John.
In regards that pork shoulder (aka pork butt). Some controvery on what temp I've seen mention of everything from 180 to 205. I also shoot for an internal of 205 (and I check several places before I'm sure -- it's hard to get a good consistent read on pork lots of fat can throw the reading off). If it's a small pork butt, I might cook it only to 190. I go on my instincts more than my polder...
I've also seen everything from 1 hour to up to 2 1/2... yes really.
My recommendation: plan for 1 1/4 hours per pound, but don't do this blindly. I start checking mine about 1/2 way through my estimate and keep and eye on it when I'm mopping it.
I'm not a fan of foil but it does a great job of keeping the moisture in. My complaint is that I want some of the "renowned Mr. Brown" bark with my butt and you can't get that with foil -- it's too "mushy". Now what I have done is finish them off in foil to get them moist and then pop them on the grill for 10-15 to crisp up the outside.
It's also hard to get some mop onto the meat. A good vinegar based mop does wonder for pulled pork.