Landmark also got an important update today, the biggest part of which is the addition of a party system. While there is no specific UI for it yet, players can invite friends to a group through slash commands, via a friends list, or by right-clicking on them in the world. Groups earn a 20% bonus to harvested loot.
The update also added in-game email, social media integration, and the ability to teleport to the continent hub or to your friends.
[Update: The Landmark team has also posted to explain the differences between time-limited beta keys and founder packs.]