So far there is:
Large Wood Spike Wall
Small Wood Spike Wall
Supply Signal (Only from Airdrops/Killing Players, Cannot be researched or crafted, Unsure about Zombie/Mob drops)
Neither of these require foundation and can be placed anywhere (Thank god)
Spike Walls can be placed on rock/cliffs.
Wood Gate takes 1 C4, Wood Gateway took 40.
Small Wood Spike Wall took 3 C4 to blow up.
Large Wood Spike Wall was claimed by an admin to take 20 C4, although it’s unsure at the moment.
I’ve noticed large performance increases (Even on my garbage PC) also new sounds when walking on wood, grass and hatcheting wood, etc.
Small Spike Wall did about 30 damage when walking into, after staying for an additional 1 second the damage doubled.
When throwing the Supply Signal, it automatically brings in an airdrop right on top of you.
Some images of the Gateway opened/closed and large spike wall base defenses for the win.