The insulation contractor has completed the foaming and caulking of openings in the exterior walls (and a lot of holes drilled in the top and bottom plates of walls for electrical and other wiring). And then they came in and blew in the cellulose insulation. This is a cool system, they use shredded newspaper that's treated with an agent to inhibit mold and make it flame-retardant. They spray it in wet. The insulation fills the cavity between studs and is trimmed flush with the exposed faces of the studs, so there's very little air infiltration. When combined with the foam and caulk package, this is a very effective insulation technique.

Here's some pics of the installed stuff. The most noticeable change is that there's no more echo. When I pull my truck into the garage and turn up the radio, I can't hear it as well throughout the house. Plus it's nice and warm inside the house now.