Well, got more interesting today when I went out for a short drive and
a quick plow (broken or not, the snow gotta move!)

Noise got quickly worse and worse. I then realized my brake peddle was
going down way too far--I'd lost brakes at one end or the other. I
figure the front as I just yesterday did the rear brakes, and I'm
reasonably comfident in my work (and rear brakes are simple enough to
do!) to think that they are OK. As well it seems now the noise (much,
much worse, grinding, squeeling, and making other bad, bad sounds)
seems to be coming from the front, perhaps driver's side, wheel.

Tomorrow I've someone else who will plow my driveways so my customers
won't feel too badly, then I'll start tearing down the front end.

I suspected front axle U joints, but they were replaced by the dealer
only a few thousand miles ago, and don't see anything visually wrong
with them at this stage. I know my ball joints in the front are a bit
worn (again, another great move: non-greasable ball joints in a
truck!) but when they fail it is not noise that you hear but the
screams of people saying: "Look out for that wheel!" <g>

Time to start tearing down the rest of the front end. My inspection
the other day was limited to looking to see how much pad I had left,
so it must be something else. I'm thinking I may have a delaminated
pad, but I'm not sure.