Looking at the E3 footage of the crafting system, I just realized some of the grip mods (the stocks to be specific) say "improved melee damage" in the description. Does this perhaps mean we're getting to bump enemies on the head with our guns in melee? I'm into that.

Yeah. If you watch the combat footage, you see the PC smacking a raider in the head twice with the butt of a 10mm pistol. You can also attach bayonets to weapons.