A button, switch or lever a friend presses is pressed in your game too, so the door, elevator or light it drives reacts for you as well (reported on Nexus: "when the friend presses the button, the door doesn't open").
A friend's stand-in no longer throws a grenade of its own when their throw is replayed; you only get their explosion where it really happened.
Protocol unchanged: 0.7.0 to 0.7.2 play together, but only players on 0.7.2 see each other's button presses.
Dev: refs, trace commands and a movement-sync harness; tools\package.ps1 -Nexus builds the Nexus zip without the dedicated-server exe.