Lots of EXCELLENT discussion here.
As I said, I've got handguns now that weight under 24oz. loaded. It's the new conceal carry BUGs (back up guns) that are really interesting because they cut the weight in half of what I now own. As more states (41 now) adopt Conceal Carry License laws, manufactures will more and more meet the demands of lighter weight and more easily carried sidearms, and this works right into the 'ultralight' backing philosophy.

As far as packable rifles go, I can speak about two.....Win. model 94 30-30, and Ruger 10/22. Off all the rifles I've owned I keep coming back to those two. Both easily packable (on slings), light, rugged, and they just plain work. The 30-30 round is a pig ballistically, but I've not found anything it won't drop in 100m. In Texas it, or the Marlin version, is the standard "brush gun". I like iron sights.

The Ruger 10/22 is lightweight and modeled after the M-1 carbine (which is my second choice over the 30-30). For small game or just plinking around, they run all day and can go a lifetime without cleaning.

Shotguns...the Rem 870LT, 20ga. Built in a .410 frame, with mahagony stock and forend. It's almost too light.