This morning, I changed the plugs using the how-to from CF (big thanks to shinermiller):
Spark plugs were overdue (I'm at 120K miles), but they didn't look bad - just old and somewhat worn. I was hoping #1 spark plug (passenger's side front plug) was going to be looking really crappy, but it looked like normal wear:
Truck will not start. Too hot out to mess with this now. In the morning, I'm going to spray some starting fluid down the throttle body to see if that will help (maybe a fuel issue is causing the no start condition).